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    Basically a Pump is used for liquid or fluid to transform it to a much high pressure head while a Compressor is used for gases to transform from low to a much high pressure. From Mechanical Engineering point of view liquid is incompressible so Compressor cannot be used for liquid substances. Posted by AbdulQadir Abba Sheriff on linkedin
  2. 34 likes
    1. What is the difference between scavenging and supercharging ? Ans: Scavenging is process of flushing out burnt gases from engine cylinder by introducing fresh air in the cylinder before exhaust stroke ends. Supercharging is the process of supplying higher mass of air by compressing the atmospheric air. 2. What are the names given to constant temperature, constant pressure, constant volume, constant internal energy, constant enthalpy, and constant entropy processes.Ans: Isothermal, isochroic, isobaric, free expression, throttling and adiabatic processes respectively. 3. In a Rankine cycle if maximum steam pressure is increased keeping steam temperature and condenser pressure same, what will happen to dryness fraction of steam after expansion ?Ans: It will decrease. 4. Why entropy change for a reversible adiabatic process is zero ? Ans: Because there is no heat transfer in this process. 5. What are two essential conditions of perfect gas ? Ans: It satisfies equation of state and its specific heats are constant. 6. Enthalpy and entropy are functions of one single parameter. Which is that ? Ans: Temperature. 7. Why rate of condensation is higher on a polished surface compared to rusty surface ? Ans: Polished surface promotes drop wise condensation and does not wet the surface. 8. How much resistance is offered to heat flow by drop wise condensation ? Ans: Nil How are these questions - please do add comments and if you like them please do share this post on facebook, linkedin, twitter and google plus. 9. What is the relationship between COP of heating and cooling ? Ans: COP of heating is one(unity) more than COP of cooling. 10. How much is the work done in isochoric process ? Ans: Zero. 11. When maximum discharge is obtained in nozzle ? Ans: At the critical pressure ratio. 1. Under what condition the work done in reciprocating compressor will be least ? Ans: It is least when compression process approaches isothermal. For this purpose, attempts are made to cool the air during compression. 13. What is the difference between stalling and surging in rotary compressions ? Ans: Stalling is a local phenomenon and it occurs when How breaks away from the blades. Surging causes complete breakdown of flow and as such it affects the whole machine. 14. Why the electric motor of a fan with backward curved blades is never got overloaded under any condition ? Ans: The maximum power is consumed at about 70% of maximum flow in case'of fan with backward blades. For higher flow, power consumption gets lower. 15. Why the work per kg of air flow in axial flow compressor is less compared to centrifugal compressor for same pressure ratio ? Ans: Isentropic efficiency of axial flow compressor is higher. 16. What is the name given to portion of thermal energy to be necessarily rejected to environment ? Ans: Anergy. 17. What is pitting ? How it is caused ? Ans: Non uniform corrosion over the entire metal surface, but occuring only in small pits is called pitting. It is caused by lack of uniformity in metal. 18. What is caustic embrittlement ? Ans: It is the actual physical change in metal that makes it extremely brittle and filled with minute cracks. It occurs particularly in the seams of rivetted joints and around the rivet holes. 19. Which impurities form hard scale and which impurities soft scale ? Ans: Sulphates and chlorides of lime and magnesium form hard scale, and carbonates of lime and magnesium form soft scale. 20. What is the difference between hard water and soft water ? Ans: Hard water contains excess of scale forming impurities and soft water contains very little or no scale forming substances. 21. Which two elements in feed water can cause corrosion of tubes and plates in boiler ? ' Ans: Acid and oxygen in feed water lead to corrosion. 22. What should be done to prevent a safety valve to stick to its seat ? Ans: Safety valve should be blown off periodically so that no corrosion can take place on valve and valve seat. 23. Why large boilers are water tube type ? Ans: Water tube boilers raise steam fast because of large heat transfer area and positive water circulation. Thus they respond faster to fluctuations in demand. Further single tube failure does not lead to catastrophy. 24. What type of boiler does not need a steam drum ? Ans: Super-critical pressure boiler. 25. Why manholes in vessels are usually elliptical in shape ? Ans: Elliptical shape has minimum area of opening and thus plate is weakened the least. Further it is very convenient to insert and take out the cover plate from elliptical opening. 26. Low water in boiler drum is unsafe because it may result in overheating of water tubes in furnace. Why it is unsafe to have high water condition in boiler drum ? Ans: High drum level does not allow steam separation to be effective and some water can be carried over with steam which is not desirable for steam turbine. 27. Why boiler is purged everytime before starting firing of fuel ? Ans: Purging ensures that any unburnt fuel in furnace is removed, otherwise it may lead to explosion. 28. What is the principle of mechanical refrigeration ? Axis. A volatile liquid will boil under the proper conditions and in so doing will absorb heat from surrounding objects. 29. Why high latent heat of vaporisation is desirable in a refrigerant ? Ans: A high latent heat of vaporisation of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage. 30. What is the critical temperature of a refrigerant ? Ans: Critical temperature is the maximum temperature of a refrigerantrat which it can be condensed into liquid and beyond this it remains gas irrespective of pressure applied. 31. Maximum combustion temperature in gas turbines is of the order of 1100 to 10°C whereas same is around 00°C in I.C. engine ? Why ? Ans: High temperature in I.C. engine can be tolerated because it lasts for a fraction of second but gas turbines have to face it continuously which metals can't withstand. 32. Why efficiency of gas turbines is lower compared to I.C. engines ? Ans: In gas turbines, 70% of the output of gas turbine is consumed by compressor. I.C. engines have much lower auxiliary consumption. Further combustion temperature of I.C. engines is much higher compared to gas turbine. 33. What do you understand by timed cylinder lubrication ? Ans: For effective lubrication, lub oil needs to be injected between two piston rings when piston is at bottom of stroke so that piston rides in oi during upward movement. This way lot of lub oil can be saved and used properly. 34. What is IIUCR in relation to petrol engine ? Ans: HUCR is highest useful compression ratio at which the fuel can be used in a specific test engine, under specified operating conditions, without knocking. 35. In some engines glycerine is used in place of water for cooling of engine. Why ? Ans: Glycerine has boiling point of 90°C which increases its heat carrying capacity. Thus weight of coolant gets reduced and smaller riadiator can be used. 36. Why consumption of lubricating oil is more in two-stroke cycle petrol engine than four-stroke cycle petrol engine ? Ans: In two-stroke engine lub oil is mixed with petrol and thus some lub oil is blown out through the exhaust valves by scavenging and charging air. There is no such wastage in four stroke petrol engine. 37. As compression ratio increases, thermal n increases. How is thermal n affected by weak and rich mixture strength ? Ans: Thermal n is high for weak mixture and it decreases as mixture strength becomes rich. 38. How engine design needs to be changed to burn lean mixture ? Ans: Engine to burn lean mixture uses high compression ratio and the highly turbulent move¬ment of the charge is produced by the geometry of the combustion chamber. 39. Horse power of I.C. engines can be expressed as RAC rating, SAE rating, or DIN rating. To which countries these standards belong ? Ans: U.K., USA and Germany respectively. 40. What is the use of flash chamber in a vapour compression refrigeration cycle to improve the COP of refrigeration cycle ? Ans: When liquid refrigerant as obtained from condenser is throttled, there are some vapours. These vapours if carried through the evaporator will not contribute to refrigerating effect. Using a flash chamber at some intermediate pressure, the flash vapour at this pressure can be bled off and fed back to the compression process. The throttling process is then carried out in stages. Similarly compression process is also done in two separate compressor stages. 41. Why pistons are usually dished at top ? Ans: Pistons are usually hollowed at top to (i) provide greater spa'e for combustion, (ii) increase surface for flue gases to act upon, and (iii) better distribution of stresses. 42. What is the function of thermostat in cooling system of an engine ? Ans: Thermostat ensures optimum cooling because excessive cooling decreases the overall efficiency. It allows cooling water to go to radiator beyond a predetermined temperature. 43. What are the causes of failure of boiler tubes ? Ans: Boiler tubes, usually are made from carbon steel and are subject to (a) high rates of heat transfer,( b ). bending stresses due to uneven heating, especially at expanded or welded joints into headers or drums, © external erosion from burners and flue gas, (d) possible corrosion on the boiler side, and (e) occasional manufacturing defects. Failure may occur due to following reasons : (a) High thermal ratings may lead to rapid failure if the internal fluid flow is reduced for any reason. The resultant overheating leads to a failure by creep, characterised by the bulging of the tube with the eventual development of a longitudinal split. (b ) Fatigue cracking due to bending stresses occur. These are associated with change of section and/or weld undercut, where tubes are expanded or welded into headers. © Failure may arise due to overstressing of a reduced section of metal. (d) Sudden failure of the boiler tube due to corrosion arises from embrittlement of the carbon steel due to interaction between atomic hydrogen from the corrosion process and the iron carbide present in the steel. (e) Defects in tube manufacture, although far from being a regular occurrence, can be a cause of serious trouble. Lamination in boiler tubes or score marks arising from the cold drawing of tubes, give rise to premature failure and may promote corrosion at these regions. 44. What are the causes of failure of superheater tubes ? Ans: Superheater tubes are subjected to the most severe combination of stress, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be used at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr. Failures in superheater tubes may arise from : (a) Prior fabrication history (b ) Faulty heat treatment © Consequences of welding (d) Overheating of the tube metal (e) Gas-side corrosion (f) Stress corrosion (austenitic steels). 45. Why supercritical boilers use less amount of steel compared to non-supercritical boilers ? Ans: Supercritical boilers do not head heavy drum for separation of steam from mixture of water and steam. 46. Out of electric heater and heat pump, which is economical in operation ? Ans: Heat pump. 47. Which furnace burns low-ash fusion coal and retains most of the coal ash in the slag? Ans: Cyclone furnace. 48. How the thickness of thermal boundary layer and thickness of hydrodynamic boundary layer related ? Ans: Ratio of their thickness = (Prandtl number)-1/3. 49. What is the effect of friction on flow of steam through a nozzle ? Ans: To decrease both mass flow rate and wetness of steam. 50. Why gas turbine power plant needs efficient compressor ? Ans: Because a large portion of turbine work is eaten away by compressor and its inefficiency will affect net power output and cost of generation. 51. Why rockets using liquid hydrogen have higher specific impulse compared to liquid hydrocarbon ? Ans: Liquid hydrogen has higher burning velocity. 52. Why axial flow compressor is preferred for gas turbines for aeroplanes ? Ans: Because it has low frontal area. 53. What is the effect of inter cooling in gas turbines ? Ans: It decreases thermal efficiency but increases net output. 54. Why iso-octane is chosen as reference fuel for S.I. engines and allotted 100 value for its octane number ? Ans: Iso-octane permits highest compression without causing knocking. 55. Why thermal efficiency of I.C. engines is more than that of gas turbine plant ? Ans: In I.C. engine maximum temperature attained is higher than in gas turbine. 56. Which are the reference fuels for knock rating of S.I. engines ? Ans: n-heptane and ISO-octane. 57. When effect of variations in specific heats is considered then how do maximum temperature and pressure vary compared to air standard cycle ? Ans: Temperature increases and pressure decreases. 58. Quantities like pressure, temperature, density, viscosity, etc. are independent of mass. What are these called ? Ans: Intensive properties. 59. The amount of radiation emitted per scm per sec is called .... ? Ans: Emissive power. 60. In convection heat transfer, if heat flux intensity is doubled then temperature difference between solid surface and fluid will ? Ans: Get doubled. 61. How you can define coal ? Ans: Coal is a naturally occurring hydrocarbon that consists of the fossilised remains of buried plant debris that have undergone progressive physical and chemical alteration, called coalification, in the course of geologic time. 62. Which pollutant is major greenhouse gas and what is its effect ? Ans: CO is major greenhouse gas and it traps the radiation of heat from the sun within earth's atmosphere. 63. In order to increase efficiency and reduce CO emissions and other emissions, clear coal technologies are receiving major attention. What are these ? Ans: (i) Advanced pulverised and pressurised pulverised fuel combustion. (ii) Atmospheric fluidised bed combustion and pressurised fluidised bed combustion. (iii) Supercritical boilers. (iv) Integrated gasification combined cycle systems. (v) Advanced integrated gasification, including fuel cell systems. (vi) Magneto hydrodynamic electricity generation. 64. What are the important operational performance parameters in design of fuel firing equipment ? Ans: Fuel flexibility, electrical load following capability, reliability, availability, and maintenance ease. 65. What is the differenc between total moisture and inherent moisture in coal ? Ans: The moisture content of the bulk as sampled is referred to as total moisture, and that of the air dried sample is called inherent moisture. 66. Proximity analysis of coal provides data for a first, general assessment of a coal's quality and type. What elements it reports ? Ans: Moisture, volatile matter, ash and fixed carbon. 67. Ultimate analysis of coal is elementary analysis. What it is concerned with ? Ans: Carbon, hydrogen, nitrogen, and sulphur in coal on a weight percentage basis. 68. Explain the difference between AFBC, BFBC, PFBC and PCFB in regard to fluidised bed technologies. Ans: AFBC (Atmospheric fluidised bed combustion) process consists of forming a bed of inert materials like finely sized ash or ash mixed with sand, limestone (for sulphur removal), and solid fuel particles in a combustor and fluidising it by forcing combustion air up through the bed mixture. The gas flows thorugh bed without disturbing particles significantly but gas velocity is high enough to support the total weight of bed (fluidisation). At slightly higher velocity excess gas passes through the bed as bubbles (fluidised bed) and gives the bed the appearance of a boiling liquid. Bubbling fluidised bed combustion (BFBC) has a defined height of bed material and operates at or near atmospheric pressure in the furnace. Pressurised fluidised bed combustion (PFBC) system operates the bed at elevated pressure. Exhaust gases have sufficient energy to power a gas turbine, of course, gases need to be cleaned. In fluidised combustion, as ash is removed some unburned carbon is also removed resulting in lower efficiency. In circulating fluidised bed combustion (CFBC) system, bed is operated at higher pressure leading to high heat transfer, higher combustion efficiency, and better fuel feed. Circulating fluidised beds operate with relatively high gas velocities and fine particle sizes. The maintenance of steady state conditions in a fast fluidised bed requires the continuous recycle of particles removed by the gas stream (circulating bed). The term circulating bed is often used to include fluidised bed sys¬tems containing multiple conventional bubbling beds between which bed material is exchanged. 69. What for Schmidt plot for is used in heat transfer problems ? Ans: Schmidt plot is a graphical method for determining the temperature at any point in a body at a specified time during the transient heating or cooling period. 70. In which reactor the coolant and moderator are the same ? Ans: Pressurised water reactor. 71. Which reactor has no moderator ? Ans: Fast breeder reactor. 72. What are thermal neutrons ? Ans: Thermal neutrons are slow neutrons (having energy below 1 eV) which are in thermal equilibrium with their surroundings. 73. What is big advantage of fast breeder reactor ? Ans: It has rapid self breeding of fissile fuel during the operation of the reactor, and thus, it offers about sixty times the output with same natural uranium resources through ordinary non-breeder nuclear reactor. 74. What is the purpose of biological shield in nuclear plants ? Ans: Biological shield of heavy concrete prevents exposure to neutrons, beta rays and gamma rays which kill living things. 75. Which two elements have same percentage in proximate and ultimate analysis of coal? Ans: Moisture and ash. 76. On which analysis is based the Dulong's formula for the heating value of fuel ? Ans: On ultimate analysis. 77. Which element causes difference in higher and lower heating values of fuel ? Ans: Hydrogen. 78. Which heating value is indicated by a calorimeter and why ? Ans: Gross heating value because steam is condensed and heat of vapour formed is recovered. 79. State the difference between ultimate and proximate analysis of coal ? Ans: In ultimate analysis, chemical determination of following elements is made by weight: Fixed and combined carbon, H, O, N, S, water and ash. Heating value is due to C, H and S. In proximate analysis following constituents are mechanically determined by weight. Moisture, volatile matter, fixed carbon and ash. Heating value is due to fixed carbon and volatile matter. 80. What is fuel ratio ? Ans: Fuel ratio is the ratio of its % age of fixed carbon to volatile matter. 81. How the analyses and calorific values of fuels can be reported ? Ans: It may be reported as (a) as received or fired (wet) basis (b ) dry or moisture free basis © combustible or ash and moisture free basis 82. What is the difference between nuclear fission and fission chain reaction. Ans: The process of splitting of nucleus into two almost equal fragments accompanied by re¬lease of heat is nuclear fission. Self sustained, continuing, sequence of fission reactions in a con¬trolled manner is fission chain reaction. 83. Explain difference between fissile and fertile materials. Ans: The materials which can give nuclear fission e.g. U 35, Pu 39, U 33 are fissile materi¬als. Fertile material itself is not fissionable, but it can be converted to a fissionable material by irradiation of neutrons in a nuclear reactor. 84. What do you understand by fuel cycle in nuclear plants ? Ans: Fuel cycle a series of sequential steps involved in supplying fuel to a nuclear power reactor. The steps include : Mining, refining uranium, fabrication of fuel elements, their use in nuclear reactor, chemical processing to recover remaining fissionable material, re-enrichment of fuel from recovered material, refabrication of new fuel elements, waste storage etc. 85. What is heavy water and what is its use in nuclear plants ? Ans: Water containing heavy isotopes of hydrogen (Deuterium) is known as heavy water. Heavy water is used as a moderator. Heavy water has low cross section for absorption of neutrons than ordinary water. Heavy water slows down the fast neutrons and thus moderates the chain reaction. 86. What is a converter reactor ? Ans: A reactor plant which is designed to produce more fuel than it consumes. The breeding is obtained by converting fertile material to fissile material. 87. Explain nuclear reactor in brief. Ans: A plant which initiates, sustains, controls and maintains nuclear fission chain reaction and provides shielding against radioactive radiation is nuclear reactor. 88. What is the difference between conversion and enrichment ? Ans: The process of converting the non fissile U 38 to fissile U-35 is also called "Conversion". The material like U 38 which can be converted to a fissile material by the neutron flux is called "fertile material". The conversion is obtained within the nuclear reactor during the chain reaction. Enrichment is the process by which the proportion of fissile uranium isotope (U-35) is increased above 0.7% (original % in natural uranium). The concentration of U-35 in the uranium hexafluoride is increased from the 0.7% in natural uranium to to 4%. This is called enrichment and is accomplished in an enrichment plant. 89. Disposal of radioactive waste materials and spent fuel is a major and important technology. How the waste radioactive material is disposed off ? Ans: Nonusable fission products are radioactive and take short/medium/long time for radioactive decay to reach safe level of radioactivity. Accordingly three methods of disposal are : (a) Zero or low radioactivity material is dispersed or stored without elaborate shielding. (b ) Medium radioactivity material is stored for short duration of about 5 years to allow decay of radioactivity. © High radioactive material. They are stored in water for several months to permit radioactive decay to an accepetable low level. 90. Which nuclear reactor uses water as a coolant, moderator and reflector ? Ans: Pressurised water reactor. 91. Which reactor produces more fissionable material than it consumes ? Ans: Breeder reactor. 92. Which reactor uses natural uranium as fuel ? Ans: Gas cooled reacator. 93. Which reactor uses heavy water as moderator ? Ans: CANDU. 94. Which reactor requires no moderator ? Ans: Breeder reactor. 95. Which reactor uses primary coolant as fluoride salts of lithium, beryllium, thorium and uranium ? Ans: Molten salt breeder reactor. 96. Why an increase in area is required to produce an increase of velocity in case of supersonic flow ? Ans: Increase in area for increase in velocity for supersonic flow is required because the density decreases faster than velocity increases at supersonic speeds and to maintain continuity of mass, area must increase. 97. Under what circumstances would there be an increase in pressure in a diver¬gent nozzle ? Ans: For subsonic flow at inlet section of a diffuser a lower velocity and higher pressure will exist at the exit section. For supersonic isentropic flow at the inlet section a higher velocity and lower pressure will exist at the exit but if a shock wave occurs in the diffuser then a higher pressure will exist at the exit. 98. Why water can't be used as refrigerant for small refrigerating equipment ? Ans: The refrigerant should be such that vapour volume is low so that pumping work will be low. Water vapour volume is around 4000 times compared to R- for a given mass. 99. Which parameter remains constant in a throttling process ? Ans: Enthalpy. 100. What is the difference between isentropic process and throttlinglprocess ? Ans: In isentropic process, heat transfer takes place and in throttling process, enthalpy before and after the process is same.
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    ANSYS offers engineering simulation solution sets in engineering simulation that a design process requires. Companies in a wide variety of industries use ANSYS software. The tools put a virtual product through a rigorous testing procedure (such as crashing a car into a brick wall, or running for several years on a tarmac road) before it becomes a physical object. This pdf gives good start to understand and learn ANSYS
  4. 27 likes
    the world’s biggest engine, has a weight of 2.3 million kilogram. If the weight of the average adult person is 70 kilograms, this world’s biggest engine has a weight equivalent to the weight of 33,000 people. World’s Most Powerful Engine Can Light a Small Town When the world’s biggest engine is running at 102 revolutions per minute, it produces 80 million watts of power energy. If the average household bulb consumes 60 watts of energy, 80 million watts is enough power for 1.3 million bulbs. If the average house has 6 bulbs lighting at any one time, the Wärtsilä-Sulzer RTA96 engine will produce enough power to light 220,000 houses. If the average house has three occupants, this world’s most powerful engine will provide enough energy for 660,000 people. 660,000 people are the population of a small town.
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    Dear Folks, Enjoy with useful Engineers pocket guide
  6. 23 likes
    What is the difference between pump and compressor ? When we use pump and When we use compressor? You can answer this questionYou can like the best answerYou can share the question.....You can get updates of new questions on Facebook linkedin twitter & google plus
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    Posted by Mohammed sulieman in linkedin • abdulQadir i think ur answer is right and 2 make it more simple and easy 2 understand allow me 2 do this: pump: 1- used 4 incompressible fluid 2 transfer them from 1 place (low pressure) 2 another (high pressure) normally. 2- No change in fluids temp or volume when it s passed through pump. compressor: 1- use 4 compressible fluid whether 2 increase the fluid pressure or even 2 transform them from gas 2 liquid 2- there ll be a change in fluids temp, volume n pressure. in addition, da comprssor can be used along with a storage which means da output of da compressor can be stored and then used anytime unlike da pump. and there are more difference between pump and compressor if we compare them in term of applications.
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    Shaft is a mechanical element that transmit power and torque moment. Usually shafts are the elements with gears and pulleys attach on them (power transmission). The axle on the other hand is a mechanical element that does not transmit power. It can rotate or it can stand still. It is only loaded with bending moments. In vehicles, the terminology is same. The shafts that transmit power to the wheels are called drive shafts. The driven wheels have axles. Some people like to call the drive shafts axles (or half axles), from where the confusion can occur. The right term is drive shafts.
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    Machine is a device which converts any available form of energy into useful work where as engine is a device which converts heat energy to convert mechanical energy .
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    What is the difference between first angle method and third angle method in engineering drawing? Why is first angle method preferred over third angle in most of the countries?
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    As an older engineer, I am rather dismayed by what I see as the results of engineering education today. I have seen most young engineers come out of their college degree programs with a modest familiarity with come CAD program and a related Finite Element program, and an almost complete lack of capability to analyze machine components without the use of FEA. Thus they are unfamilliar with basic design calculations relating shear stress in a shaft to the power being transmitted, the shaft sped and the shaft diameter. Instead, they want to create an FEA model and run the numbers that way which is simply not the way you make any progress in designing a machine. It is certainly true that FEA allows for a good detailed stress analysis of complex geometries, something that was not possible in general by the older methods. But the results obtained are highly dependent on the skill of the user in applying the correct boundary conditions, something that is a bit of an art in itself. I have observed a tendency to even want to use FEA to do kinematics, rather than using simple, rigid body kinematic relations. This seems like pure foolishness in almost all cases. Are we not developing a tendency to lean too heavily on the computer, rather than to learn to think as engineers? I would be happy to hear some comments and discussion from others on these matters.
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    Version 1.0.0

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    INTERVIEW preparatory Syllabi, answers and HR questions for a Mechanical Engineer !
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    The Internal-Combustion Engine in Theory and Practice Volume I : Thermodynamics, Fluid Flow, Performance Second Edition, Revised by Charles Fayette Taylor Professor of Automotive Engineering, Emeritus Massachusetts Institute of Technology
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    From the album Engineering images

    An air conditioner works as a heat exchanger. It takes in warm air in your room and passes it over a set of cooling coil and then blows it back to the room as cold air. The cooling cycle of your air conditioner involves two basic processes: condensation and evaporation (you must have learned about them in school). There are 4 important components in your AC that control the cooling cycle: Compressor Condenser coils Evaporator Coils Freon- Cooling agent Compression and condensation cycle The coolant (mixed with lubricating oil*) enters the compressor as a cold low pressure gas where it is compressed. This compression increases the temperature and pressure of the coolant which converts it into a hot high pressure gas. This hot high pressure gas passes through a series of thin coil called condenser coil where it gets converted into a high pressure liquid. Whenever gas is converted into liquid heat is released. So the heat released during condensation of coolant is dissipated outside with the help of a condenser fan (located next to condenser coils). Expansion and evaporation cycle This hot high pressure liquid then passes through an other set of thin coils called evaporator coils, where it gets evaporated into a low pressure gas. As the liquid changes to gas and evaporates, it extracts heat from the surrounding warm air of your room. So the air coming in contact with these coils get cooled and is blown back to the room with the help of an evaporator fan. By the time the working fluid leaves the evaporator, it is a cool, low pressure gas. It then returns to the compressor to begin its trip all over again.
  15. 14 likes

    From the album Engines

    How the cam and follower system in an internal combustion engine work is shown in the animation of the four stroke cycle above. If you like it - do share it
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    While both devices provide a form of forced induction for internal combustion engines The primary difference lies in how the devices are powered. Turbochargers are powered by exhaust gasses. Superchargers are powered by a belt, chain link, or gears, directly to the engine (the crankshaft in most cases). Turbochargers perform better at higher rpm's do to more exhaust gases spinning the turbine which then in turn causes the compressor to draw in more air. This has a downside due to lag time which can be referred to as spooling up. Superchargers work better at low RPM's due to the direct link to the engine and lack of lag time however they are limited to rotating at a max speed matching that which the crankshaft can turn the mechanical linkage to the supercharger itself. One system not mentioned in this article is the twin charger system. This combines the benefits of both the supercharger and a turbocharger in creating a zero gap power band. The supercharger takes care of the lower RPMs while the turbo kicks in during the higher rpm's. The applications of this are mostly seen on engines with smaller displacement and a wide rpm range.
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    Why first angle and third angle method is used and why second and fourth angle method is not used? 1. You can answer this question 2. You can like the best answer 3. You can share the question...
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    THIS IS A WONDERFUL ANIMATION ON HOW AN IC ENGINE WORKS..FROM FORD DESIGN TEAM...
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    Pumps can handle both liquids and gases. But Compressor can handle only the gases due the incompressible nature of liquids.................
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    In DTSi, instead of 1 we are using 2 spark plugs. Flame front formed is able to consume more air-fuel mixture as compared with 1 spark plug, thus more complete burning and more efficiency. in DTS-Si, with addition of 2nd spark plug, what they are doing is relocating valves position. With proper designing of inlet and outlet valves you can induce extra swirl for inoming air fuel mixture. Due to turbulence, extra efforts are provided for proper mixing of air and fuel. (We can not allow petrol to go in liquid droplet form, it should be finely atomized). With well atomized air fuel mixture, efficiency increases.
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    Source Ashish K Darpe Department of Mechanical Engineering IIT Delhi Thanks to Mr. Ashish K Darpe Regards Saurabh Jain
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    Powerpoint Notes on Metal forming Topic includes— Hot &Cold working Forging Extrusion Rolling Drawing
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    Presentation on Design of- Clutch Brake Belts Chain Gears
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    An axle is a center of rotation (derived from the word axis). A shaft is a rotational power transmission device. The words are often used interchangeably. Specifically in a vehicle: An axle is often thought of as extending transversely (side to side) the full width of the vehicle - from wheel to wheel. For a motorcycle it extends to both sides of the frame through the wheel hub. A propeller shaft is a shaft that runs longitudinally (front to back) like an airplane propeller shaft. A shaft is a power transmission device, connected to a gear or coupler on both ends. An axle may or may not transmit power. An axle may just be used for a center of rotation on non-driven wheels such as the front wheel of a motorcycle. An axle may or may not be a shaft. In a rear wheel drive car, the propeller shaft is driven by the transmission and transmits that power to a rear differential. The rear differential transmits that power to the rear axle which drives the rear wheels. In this case, the "rear axle" is usually two shafts connected to either side of the rear differential and to each wheel hub.
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    A Community Built on False Values This may well prove to be the least popular thing I ever post on this blog because what I have to say may offend many. I do not say it with the intent to offend, but because I am compelled to give a warning. One of the most interesting things that has developed from my blog, Mechanics Corner, here on the ME Forum has been the opportunity to correspond directly with a modest number of readers. This has included both young men and young women scattered across India, Southeast Asia, the Middle East, and the rest the world. The majority of them are still students, still studying to become mechanical engineers. I have been somewhat amazed at the number of them that talk about (1) their strong intention to go on to graduate studies, and (2) their desire and intention to publish research while still in school, in some cases even below the baccalaureate level. I do not wish to discourage people from graduate study nor do I wish to dissuade them from publishing their work, but both of these strike me as somewhat inappropriate for an undergraduate engineering student. It appears to me that many are caught up in the ethos of academia which is misleading them with respect to what is really of value as preparation for an engineering career. Let me elaborate. Let us begin by considering two words, science and engineering. Wikipedia tells us that science means knowledge, coming from the Latin root word scientia. The same source also tells us that engineering, which is derived from the Latin root ingenium, means "cleverness," and the second root word ingeniare, meaning "to contrive or devise." These definitions point to the fundamental distinction between science and engineering. The scientists, particularly the physicist, seeks to know, particularly to find new knowledge. The engineer, on the other hand, seeks to apply existing knowledge to the solution of problems of interest to society. It is evident that these two fields are very close to each other. We cannot be clever and inventive without knowing what has been known for ages. But engineering is about the application of knowledge, while science is about the search for knowledge. Academia has lost its way. This is certainly true in the USA, in Europe, and it appears to be true in the rest of the world as well. Where the college or university once saw its role as preserving and passing along the best of human knowledge, to prepare people for a productive life, the schools have since become big businesses, focus on their influence, their endowments, and their prestige. In the past, faculty were valued for their knowledge and their ability to teach, that is, to pass along knowledge to those who studied with them. Today this has changed. Faculty are now valued for what they contribute to the image of the institution, for their reputations, for their publications which reflect favorably on the institution, and usually most of all, for the grants and other funding that they bring to the institution. (Notice that there is nothing about teaching in the present day evaluation of faculty; this is sad but it is absolutely true.) In order for a faculty member to advance today, he must be interested in and doing those things which are seen as contributing to the image of the institution. Foremost for faculty, this means grant writing, research, and publication. It explicitly excludes professional engineering practice. Thus, the vast majority of engineering faculty today have little or no experience as practicing engineers. They have a lot of experience in obtaining funding, in writing papers, in giving presentations to prestigious audiences and other similar activities that will reflect favorably on their schools. But most have never solved an actual engineering problem from industry. The reader may ask, "so how does this affect the students?" The answer is simple. The faculty talk about and praise their research, publications, and funding, and students are inclined to take these things as their own goals for the future. Thus if a student sees a faculty member advancing and doing well by publishing a lot of research (and no one ever evaluates the true value of most of that research), the student is inclined to assume that this should be their goal, their path to success as well. Nothing could be further from the truth for a baccalaureate or masters level engineer. Most of us have heard the phrase "engineering research," and what these faculty members are doing is often described as "engineering research." But is this really engineering research as it is practiced in industry? Not at all. Over the years, I have worked in industrial "research organizations" of many sorts, but very, very little of the work done in those organizations is publishable for the simple reason that it is not fundamentally new. Engineering research, as practiced in industry, in most cases means going to the library to see if you can find a paper (or a book) where the problem you are currently dealing with has been previously solved, or at least a very similar problem that can serve as a model for you. If we talk about experimental engineering research, that usually implies experiments and measurements directed to answer very specific questions about the problem at hand, and almost never about fundamental physics or other "new" knowledge. Let me cite a few examples of engineering research that I have been involved with personally: 1. Many years ago, I conducted an experimental study of the flexural vibration of a sonar transducer head under a U.S. Navy contract. The transducer head is that part of the sonar device that comes in direct contact with the water in order to transmit, or receive, a sound wave. For analytical purposes, the sonar head is usually modeled as a rigid body, but it was generally understood that being a real, physical body with flexibility, there would be a degree of flexing involved as it moved rapidly back and forth. My research quantified the extent of that flexing and suggested the possible need for further stiffening of the design. There was no fundamentally new information; no new phenomenon were discovered, and there was nothing publishable other than a report to the U.S. Navy. 2. At one time, I was employed as a research engineer at the Homer Research Laboratories run by Bethlehem Steel Corporation, conducting research in cold rolling of steel strip. My particular assignment was to develop a mathematical model and a computer simulation based on that model for the multistand cold rolling mill. A significant part of my "research" was simply going to the library to search for work previously done by others about modeling the phenomenon that occur in the roll gap where the thickness reduction actually occurs. My "research" was largely the application of work done by numerous others, and it was not in the least bit publishable, although it was a valuable engineering tool for my employer. 3. I once worked for a company that assembled engine-generator packages, using both engines and generators made by others. My principal responsibility in that position was the torsional vibration analysis of these machines, essentially the forced response analysis of a rather complicated, multi-degree of freedom vibration system, done for every machine we shipped out. Even though this was after I had completed my college work, I had never studied systems quite like that before. So "engineering research" became a matter of learning about multidegree of freedom vibration analysis, becoming familiar with the modal method, learning about the Holzer calculation technique, and refreshing my memory about the application of Fourier series. Not a bit of this was new. Multidegree of freedom vibration goes back at least as far as the Lord Rayleigh in the mid-19th century if not earlier, the Holzer calculation dates from the early 20th century, and Fourier series date from the early 19th century. So, while there was nothing new in any of this, it was necessary "engineering research" in order to give me the capability to perform my assigned tasks. 4. While at the engine-generator company, I was asked to create a mathematical model and numerical dynamic simulation for a complex system consisting of a diesel engine with the governor, a generator with its exciter, and induction motor, and a pump. This system is the emergency core cooling system for a nuclear power plant. In the event of the loss of regular coolant flow to the core, the standby diesel engine is started and the speed stabilized by the governor. After this is done, the exciter is activated to apply the field to the generator windings, and power is delivered to the induction motor. This step again requires stabilizing the speed by the governor. The induction motor is rigidly coupled to the pump which provides water to cool the core. All of these steps must happen very quickly, typically in about 15 seconds, so there is a lot going on. In my own engineering education, I had learned about basic circuit theory, but I never studied much about motors and generators. Thus my "engineering research" at this point included a lot of study of motor/generator theory, all information that had been known since the early 20th century. There was nothing about the eventual simulation that was publishable research, but it was a valuable engineering tool for my company. The point of the four little stories above is simply that, in most cases of engineering practice, "engineering research" is simply a matter of finding existing knowledge so that it may be applied to a current problem of interest to the employer. Only in the most rare circumstances is it about the search for new knowledge, knowledge previously unknown to anyone. And yet it is this last, the search for new knowledge that is the focus of most academic research. With some exceptions, academic research is rarely relevant to the actual problems of industry today. Let me also make a few comments about graduate education. Without going into the broad topic of the degradation of education at all levels, let it suffice to say that there are, broadly speaking, two categories of engineers. Let us call the first category the Project Engineer, almost always an individual with a baccalaureate degree in engineering. The second category, which we will call the Advanced Engineer, is usually a person with a Masters or doctoral degree in engineering, although baccalaureate degree holders are not entirely excluded. The Project Engineer has broad responsibilities for many types of projects, including design, manufacturing considerations, obtaining materials, meeting delivery schedule requirements, and resolving difficulties as they arise. He relies heavily on codes and standards in his design work, often employing "rules of thumb" instead of rigorous calculation; this is how the vast majority of engineering gets done. The Project Engineer draws on his engineering education background for understanding, but rarely makes a calculation and relies heavily on engineering intuition to do his job. The Advanced Engineer is one who has chosen to deepen his technical expertise, and enjoys dealing with more complicated problems, particularly in terms of mathematical analysis. The Advanced Engineer may, but often does not, have broad project responsibilities, but he is expected to be more rigorous in his work and to have a greater knowledge base. He is often seen as a resource person for the Project Engineer. Industry in every country needs large numbers of Project Engineers; this is where the jobs are for most engineering graduates. Industry in every country needs a far smaller number of Advanced Engineers because their role is largely support for the Project Engineers. At times, when there is a great industrial surge, such as the USA experienced during the space program, there is a somewhat increased need for Advanced Engineers, but there is always a greater need for Project Engineers. Even when times are good, when industry is hiring many engineers, too much education can often be a disadvantage for a job seeker. The employer, seeking a Project Engineer, will often say when considering a person with an advanced degree, "This person has more education than my position requires. This candidate is likely to become dissatisfied with the job after I invest in training him to do it. It is better to hire someone with less education who will remain with my company indefinitely." I have seen this happen, and I have been a victim of it myself. Thus I encourage all to think carefully about their goals and their potential employment prospects when considering whether to go to graduate school or not. Let me tell one more personal experience to illustrate the difference between the Project Engineer and the Advanced Engineer. 5. Not quite 20 years ago, I was employed by a manufacturer of aerospace components. A dispute arose with the US Federal Aviation Authorities (FAA) regarding the design adequacy of a particular component in one of our products. The component was a push rod, bent into what is sometimes called a "dog-leg" configuration (a sort of Z-shape), and is operated in both tension and compression. The FAA inspector argued that the pushrod might fail by buckling, and our project engineer was unable to convince him otherwise. The problem came to me to justify our design. Now buckling is an instability phenomenon, and I saw immediately that because of the bent configuration of the rod, there was no possibility of instability but only further bending, and hence no possibility of buckling. This argument, however, did not persuade the FAA inspector. My only option, therefore, was to calculate the deflections of the pushrod when operated in compression. This is not a simple calculation, and no one in my company knew how to do it. I turned to the classic book on elastic instability of structures by the great Ukrainian engineer Stephen Timoshenko where I found a similar, slightly simpler, problem that I could use as a model. Following Timosheno's work, I made the calculations to show that there simply was no buckling potential, and that further the very most elementary deflection calculations gave an almost identical result. The FAA inspector was unable to respond. I mentioned this last personal experience in part to show (1) my role as the Advanced Engineer in support of the Project Engineer, (2) and also to show how, in this case, "engineering research" amounted largely to resorting to the literature for results almost 100 years old. Once again, it must be noted that this "research" produced no new results and was therefore not publishable, but it was worth a lot of money to my company. Well, if students are being misled by academia about the nature of actual engineering, what can they do about it? The answer is simple to describe, even though it may be more difficult to put into practice. The short answer is, "Look for actual engineering experience for yourself outside of academia." How is this accomplished? 1. One of the classic ways to gain real experience has always been to look for work opportunities during the summer or other school vacation period in actual industry. Now it is obvious that working as a sacker in a grocery store will not provide much useful experience for someone who aspires to be come a machine design engineer. But work in a factory, on an assembly line, or even just distributing parts to an assembly line, will provide much useful insight into the nature of engineering work, the work environment, the demands, the expectations, and the hazards. If if you cannot get engineering work as an undergraduate, there is valuable experience to be gained simply by working around engineers. 2. In the USA, many engineering colleges provide a work/study program called Cooperative Education (Co-Op for short) in which a student, usually beginning in the second year, goes to school for one term and then goes to work in some actual industrial environment for the next term, alternating this pattern until graduation. Many students spend all their Co-Op work terms with the same company, but others will sample several different companies. If a student does well during his work experiences, this often leads to a job offer at the end of his college education. By that time, the student understands what is expected of engineers in that particular company, and the company has a understanding of the value of that student as a permanent employee. If Co-Op is available at your school I strongly urge you to take advantage of it. 3. Look for part-time work while in school with some actual, industrial firm, where you can see and perhaps participate in actual engineering work. This is an additional burden to your school work, but the opportunity to see the connection between school work and engineering practice can be invaluable. (I had a student once who worked in a battery factory while he was taking my Theory of Machines course. He was seeing, and working with on an everyday basis, many of the exact mechanisms that we were studying in class. He got an extraordinarily good education out of the combination.) 4. The SAE (the organization formerly known as the Society of Automotive Engineers but now legally simply SAE) organizes and conducts many student design competitions for engineering students. A number of these are structured around the design and construction and eventually racing various types of small race cars. Although done within the academic context, this provides students with a real engineering experience. If your school has such a competition, I strongly urge you to be a part of it. If your school does not have such, then I urge you to ask the school to get involved with the SAE student design competitions. Let me close with one final story from my own experience, a story where I was simply an observer, not a participant at all. A company where I was employed hired two new graduate engineers, one from each of the two major engineering schools in my home state. One of the schools is known for being very practical and down to earth, while the other is known to be much more theoretical, more elegant, more research oriented. Each of these new employees was given a similar project to begin, the design of a small power transmission shaft. The graduate of the very down to earth engineering program got right to work, following steps he had learned in an undergraduate machine design class. He had an acceptable design in a matter of a few days. The graduate of the elegant, research oriented institution fumbled around for literally weeks, starting over time and again and essentially unsure how to proceed. He knew many of the things that needed to be considered, but he had no way to go about working through them systematically. It was very evident to me which one of these would make the better engineer. I urge all students therefore to keep their eyes clearly fixed on the goal of engineering (assuming that really is their goal) and not let research, publication, and advanced studies cloud their vision.
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    In second angle, both top and front view are drawn above the x-line whereas in fourth angle its vice versa. In second and fourth angle method, top view and front view overlaps. hence we never use those methods. In first angle method, front view lies above the x-line and top view lies below. vice versa for third angle. As both the views lies on either side of x-line in first & third angle, we make use of these methods.
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    Dear Mechanical Engineering members, I want you all to visit iMechanical Engineering Forum once every day and for same I am starting "Attendance Please" Post. Many of us read as guests, some of them just sign in and sign out and then I request every one to mark your attendance by replying to this post. Your presence will make all members active and visible on the board.
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    The question posed was, "Is mechanical engineering good for girls?" but I would like to take a contrarian position and ask the opposite question, "Are girls good for mechanical engineering?" I have no doubt that young women are able to complete the educational process and to perform the job (at least some of them are), but are they a good investment of our educational resources? Most young women will want to marry; it is a natural thing. With marriage come additional family responsibilities, a husband, children, a home to manage. This usually leads to one of two possible ends: (1) they drop out of engineering completely after a few years; or (2) they only dabble in engineering, working part time, working things that suit their schedule and other responsibilites, etc. In contrast, when a man takes a job, as an ME or anything else, he can usually be counted upon to remain on that job, full time, fully committed, indefinitely. He has a wife and family to support, and a career to build. He cannot be casual about his committment to his job and his profession. Why did we spend the educational resources to train the young woman, possibly to the exclusion of a young man, when she is only a temporary/part time engineer? I am a retired ME professor, and I have seen a fair number of young women come through my classes. Some of them did absolutely brilliantly, but to the best of my knowledge, none of them is a full time practicing engineer today. I was in contact last summer with a young woman who had been in my classes years ago. She was a star student and has since gone on to complete a PhD in ME. But, she is also a wife and mother. We were discussing working together on a project. She said that she was interested in the project, but not right now. It was summer time, and she wanted to ride her bicycle and play with her kids during the summer. To my mind, she is simply not serious about being an engineer, even though she is extremely bright. I think there is grave doubt about whether young women belong in engineering of any sort.
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    Most of the time gears are used for reduction. So pinion is smaller as compared to gear, i.e. no of teeth on pinion are less as compared to gear. This in accordance affects the number of cycles. Thus in any operation, pinion performs more cylces as compared to gear. More cycles means more wear and hence generally pinion material is selected such that its hardness is more than material of Gear.
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    Basic Difference is the how their are measured.. [1] i.e. A pipe is measured by ID(inner diameter) and a tube is measured by OD(outer diameter). [2] a pipe is like a vessel to store a liquid/gas so inside volume is important factor, while a tube is seen as structual member so total volume is important factor.
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    air conditioning is not only related to cooling air.. its about controlling temperature, humidity, purity and flow of air throughout the area.. Refrigeration is only related about reducing temperature..
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    Mechanical Engineering Interview Questions and answers for freshers on design, safety and maintenance. 1) What is an accident ? An accident is a unexpected and unforeseen event which may or may not injury to a person or a machine tool. 2) What are the standard sizes of drawing board as per Indian Standards? As per Indian Standards :1250×900,900×650,650×500,500×350,350×250 sizes are available. 3) What are the functions of a scale ? (a) To measure distance accurately. (b) For making drawing to scale either in full size, reduced size or enlarged size. 4) What is a sketching ? This is freehand expression of the graphic language. 5) What do you mean by First Aid ? First Aid is immediate and temporary care given to a person who affected accidental injury or a sudden illness before the arrival of doctor. 6) What is a Drawing ? It is a graphical representation of a real thing to define and specify the shape and size of a particular object by means of lines. 7) What is Engineering Drawing ? A drawing which is worked out an engineer for the engineering purpose is known as Engineering Drawing. 8) What are the methods of extinguishing fire ? 1) Starvation. Separating or removing the burning material from the neighbour hood of the fire. 2) Blanketing. Preventing the air flow to the fire. 3) Cooling. Lowering the heat created by burning materials. 9) What are the precautions to be taken to avoid fire ? 1) The buckets along with sand should be placed inside the workshop. 2) Switches and other electrical parts must be made of fireproof material. 3) Carbon dioxide gas should be place at required points in special containers. 4) Fire extinguishers of suitable type should be placed at accessible places.\ 10) What safety precautions should be observed while working in the workshop ? 1) Keep shop floor clean, free from oil and other slippery materials. 2) Wear proper dress and avoid loose clothing and loose hair. 3) Wear shoes and avoid chapels. 4) Avoid playing, loose talk and funning inside the shop floor. 5) Keep good housekeeping and put all unnecessary items and rejected items in scrap box. 6) Learn everything about the machine before starting and clear all the doubts. 7) Keep a safe distance from rotating and sliding parts. 8) Never store inflammable materials inside or around the shop. 9) Never play with electricity, fire, parts with sharp edge etc. 10) Keep fire buckets and extinguishers ready for use.
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    Hi to all of you, I am attaching hypermesh notes created by me during training period. If you are in doubt at any stage then you can contact me from this forum. It is draft version of notes but still it is useful for all CAE begineers. Umesh Tak Hypermesh.pdf
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    There has always been a debate and discussion among all engineering students about which engineering course is the best? Students always love discussing about the best branch of engineering. Though this is a proven fact and it needs no discussion that mechanical engineering is the best still I will be providing 10 reasons over here which make mechanical engineering The Best among all other branches of engineering. #1 Evergreen Field: Mechanical engineering is an evergreen field. Applications of mechanical engineering have spread over such a wide spectrum that it has penetrated into almost every industry. Mechanical engineering got its application started right from the birth of this universe and it will continue till the end of this universe. #2 Mother Of All Engineering Disciplines: Yeah it’s mother of all engineering disciplines and you know it! Mechanical engineering links all engineering disciplines together and provides a base for all engineering education. #3 Everything Is Mechanical: Mechanical engineering has its application in all fields of life. May it be medicine, construction, automobile or even software and IT industry. Everything you see around you involves mechanical engineering to some extent. #4 Everlasting Scope: Scope of mechanical engineering is everlasting. Mechanical engineering graduates can find career placements in almost every sector, right from construction sector to steel industry and from automobile to software. #5 Best Job Offers: Mechanical engineers get best job offers after graduation. It’s one of the highest paid jobs all over the world. #6 Social Status: Mechanical engineers are respected in every society. They possess a respectful social status among masses. They are like global ambassadors. Wherever they go, they are treated with respect. #7 Most Interesting: Mechanical engineering involves study of some of the most interesting phenomena of science and engineering. The basic focus during study is on subjects such as thermal engineering, fluid sciences, machine design, industrial engineering and production engineering. #8 Even GOD Loves ME: Ever thought GOD also implemented mechanical engineering in nature? Motion of your body, arms, hands and feet involves mechanical engineering. Your heart pumps blood and it runs through all your veins. This is again application of mechanical engineering. The more you look into nature with the eye of a mechanical engineer, you will find more application of it. #9 Best Lifestyle: Do you need a best lifestyle to live in? Mechanical engineering offers you one of the best lifestyles. It’s like a dream come true. #10 Vast Industry: Mechanical engineering industry is vast. Every industry needs mechanical engineers to run its business smoothly. Do you have more reasons to say? Don’t forget to comment. Let us see how many reasons we can gather here in comments. I hope you enjoyed reading 10 reasons why mechanical engineering is the best course. No doubt It's best engineering course and best engineering branch!
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    A COMPLETE INSTRUCTOR AND STUDENT SUPPLEMENT PACKAGE - Continued These ppts are set of instructor and student supplements. . A FOCUS ON DIAGNOSIS AND PROBLEM SOLVING The primary focus of these ppts is to satisfy the need for problem diagnosis. Time and again, the author has heard that technicians need more training in diagnostic procedures and skill development. To meet this need and to help illustrate how real problems are solved, diagnostic stories are included throughout. Each new topic covers the parts involved as well as their purpose, function, and operation, and how to test and diagnose each system.
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    Dear Mechanical engineering professionals, Greetings from Mechanical Engineering forum , From last 6 months - I have received lots of emails and personal messages on a theme - "I am looking for a job" , "I am fresher and I need a job." I have started this blog to help you in finding your dream job.. I have to find my own ways and will welcome expert comments from the senior members to see how we can help you in getting the right job Before we contact recruiters or companies - I would like to know your answers in this posts on the question "Are you looking for a job & would you like Mechanical engineering forum to help you in finding your dream job?" The more the comments with answer yes , better will be for us to attract recruiters so that they can share hidden and un-hidden job openings on .Please do mention your location and work experience.in the comments Additionally - I will welcome ideas and suggestions to take this initiative forward. Regards Saurabh
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    Enter u r whatsapp number Share your knowledge.. And improve your knowledge My number 8870349108
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    Difference between working of centrifugal pump & reciprocating pump ?
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    I have been encouraged to contribute to the Mechanical Engineering web site by Dr. D. I have started the blog "Not Taught in Class". The purpose of the blog is to provide examples of lessons learned in the field that you would not learn in class. These stories are not white papers, just real life examples of things not expected and problems solved. The blog postings will also attempt to provide insight and perspective that comes with many years in the field of engineering. I hope the blog postings will be informative and in many cases entertaining.
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    Machine is a device to transmit force it may or may not produce power whereas Engine is used to produce power.
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    To draw a projection of any object first we need to place this object in any quardrant then fit a source of light in front, above or any angle you want. A shadow will occur in the opposite side of the light source which will represent the projection of that object. Now after drawing this projection, the horizontal plane is to be rotated 90 degree clockwise. in second and fourth angle projection due to this process horizontal and vertical plane will overlap with each other. That's why we can't draw second and fourth angle projection.
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    There is no single answer that applies in all situations. At one point in my career, I was involved in pipeline vibrations work for natural gas transmission pipelines. These pipelines use very large reciprocating compressors to move the natural gas several thousand miles. The discharge from a reciprocating compressor has highly variable pressure as the valves open, the flow moves through the valve, and then the valve closes for the next stroke. These pressure variations, referred to as "pipeline acoustics," cause the entire assembly to shake and can do much fatigue damage to the piping. Fatigue in turn leads to cracks and cracks allow leaks. This is one strong reason for pipeline leaks. DrD
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    Where Will I Find A Job?? As I read over the questions that readers post here on ME Forum and elsewhere, I sense a common theme in many of them. There seems to be a wide, dare I say almost universal, concern about where those currently in college will find employment after graduation. To a degree this is entirely understandable; we all wonder what is in our future. Even so, the level of anxiety that I sense in many of your postings strikes me as extraordinarily high. Let us consider this a bit. Most readers of ME Forum are currently enrolled in an engineering curriculum somewhere. Some are just beginning while others are nearing the end of their undergraduate education. I would like to pose a question to all of you: Why did you go to engineering school? Why did you choose what is probably one of the most difficult curricula in any college? For the sake of this article, I'm going to presume that I have heard at least some of your answers. It is almost universal among engineering students to be looking forward to a good job, one that will provide them a comfortable living and a substantial measure of security. This is not at all unreasonable, and is in fact entirely probable. Almost all of you can expect to be well employed and in the upper echelons of society wherever you live. You will not rank as high as the well-known politicians, nor will you be the most wealthy people in the area. But you will have stable work and a comfortable income from that work. What does it matter where you find employment? One of the themes I see in what I read is a great many people looking for "government jobs," that is, employment with some government entity. Traditionally, "government jobs" have been very stable. As long as a government employee stays out of trouble, in most situations it is impossible to remove that employee from his government job. This feature makes government work extremely attractive to the incompetent, to those who really cannot do the job well and thus rely on the fact that they can almost never be fired. Is this why you struggle with a difficult college curriculum, so that you can be employed with those that are incompetent? Do you really want to spend your working days with people far less capable than yourself? Many of them have achieved their positions without nearly the rigorous education that you are undergoing, so I ask you, are these the ones you want to have for your close associates? Let me tell you a personal experience. After a long career that involved both academic positions and various industrial research positions (with a few years as a solo consulting engineer), at age 59 I took a position with a research laboratory run by the U.S. Navy. It is a sad fact of life that, in the USA, most people are considered unemployable after age 60, so I was nearing the end of the time when I could look for and expect to find a new position. The job was attractive because it promised an opportunity to do some well funded work in an area I was quite interested in, the area called electro-mechanics. The position would be very stable and I would be well payed. In my first week on the job, I was given a few documents to read but nothing really to work on. I was not too surprised and expected all that to end very soon. After about three weeks in the new position with still in no work assignment, I began to be very worried. Every place I had worked previously had plenty of work to be done and anyone not given an assignment was probably being set up to be fired. I spoke with my boss about this several times, and he very casually told me not to worry about it. That really did not relieve my concern, particularly when he was so very casual about the whole matter. I tried to find things to work on, to make myself look useful and busy. In conversation with the other engineers, a few problems were suggested, and I worked on some of those. I wrote a few technical notes, primarily just to show that I wasn't simply sitting idle at my desk. Time went by, weeks turned into months, and months turned into years. When I finally retired from that position after seven years, I estimated that I had done at most 18 months of real work. The rest of the time I simply had nothing assigned for me to work on. Had I realized in the beginning how the game was to be played, I would have spent my days doing things that were much more productive, such as working on problems that I found interesting, writing technical papers on those problems, and probably writing a few books. In the nonproductive 5 1/2 years I had, I could have done a lot of work! But I did not realize how the game was played, and I kept expecting someone to assign to me real engineering work to do. As I got to know the other people, I found that a few of them had ongoing projects that were of interest to them, but most had nothing to do most of the time. I am convinced that this is the pattern of government employment, the so-called "government job." There were very few people who were truly happy in their work them: most were fairly miserable in fact. But they were wedded to the paycheck and the job security that went with their "government job." They even spoke of these factors as the "golden handcuffs." Most intended to stick it out for a total of 30 years or more, so that they could retire with a good pension. Now I ask you, the reader, is your primary goal to retire with a good pension? Is this your principal objective in life? If so, why don't you simply roll over and die now?? While it is true that no one wants to retire in poverty, most of your life is long before retirement. Retirement is the end stage of life. I have been fortunate to live almost a decade since I retired, but it is not at all uncommon for men to die within a year or two after retirement. It seems that many simply lose their purpose in life when they retire. So to live your life in preparation for retirement is foolishness of the highest order! If preparation for retirement is not to be your principal purpose, then what should be your objective? I submit to you that your objective ought to be to find meaningful, rewarding work in the service of other people. I am not suggesting that a group of mechanical engineers become social workers, but I am saying that you should see some connection between your work and the improvement of your society, the people among whom you live. If your work does nothing to help other people, what is its lasting value? The money you bring home in your paycheck will soon be spent. The time you invested to earn that money is already spent. So what are you contributing to mankind? Rather than looking for a secure, comfy do-nothing "government job," I suggest to you that you should be adventurous, looking for new opportunities and new ways to help others. This is urgently needed everywhere, particularly in developing countries. Look for small startup companies with new ideas for new products, things that will improve life for everyone. Many of these companies will fail, but you are young, and looking for another job after two or three years with the company that fails is no disaster. It will not reflect badly on you if the company fails; that reflects upon the management of the company rather than upon the engineering staff. Look also at very traditional companies that are doing things the way they have always been done. Many of these companies need engineering help if they are to remain competitive and to survive into the future. This may provide you an opportunity to keep an entire company functioning, providing employment for many people. There are countless other ways that we may help our fellow man, but this should always be high in our list of priorities for the work we will do. It is while you are young that you can afford to be adventurous, to take some risks and try out things that later in life will simply be too risky. Look for challenges, situations that will require it to you use everything that you have learned, and also require you to continue to learn. There is absolutely no point to your engineering education if your goal is simply to doze the next 50 or 60 years before you die. Plan to do something with your life, something useful, something meaningful. Do not look for a place to lay your head and simply sleep away your career.
  47. 9 likes
    The original question was, "Why is first angle method preferred over third angle?" I think in the long run, it all comes down to local custom and tradition. Both convery the same information, so neither it truly superior to the other. That said, there is one basis for a good selection that might tilt in favor of one or the other. It is desireable to minimize the number of hidden lines in a drawing, so if one method results in more hidden lines than the other, the second option is preferable. Again though, I think it is a matter of familiarity, what we are all agreed upon, all of which is known as convention.
  48. 9 likes
    Design for manufacturing, we need to prepare: -Technical description -Choose of materials for each parts -Calculation of strength or necessary other calculus for each parts -List of standard elements such as bolts and washers -Choose of machine for each parts -Calculation of necessary time for each parts -Requirements for examination for each parts and assembly Design for manufacturing, we need prepare: -Technical description -Choose of materials for each parts -Calculation of strength or necessary other calculus for each parts -List of standard elements such as bolts and washers -Choose of machine for each parts -Calculation of necessary time for each parts -Requirements for examination for each parts and assembly -Instruction for installation and maintenance -List of applied standards and regulations for the design Design for assembly, we need to prepare: -Technical description-Method statements -Time Schedule for assembly -Necessary manpower for assembly -Necessary tools for assembly -Specification of testing the entire assembly -Risk assessment This is my opinion for the general case. I apologize for the excessive descriptions, maybe ?
  49. 8 likes
    In the picture shown for the reciprocating pump, there is an error in labeling. What is labeled "CAM" is not in fact a cam at all, but rather it is a crank. What is labeled "HEAD" is in fact simply the pump cylinder wall. The head would be further to the right. The valving is usually in the head. The piston is shown extremely elongated; why? The connecting rod is not labeled at all. The implication seems to be that the seal is embedded in the cylinder wall and does not reciprocate. I see no reason why the seal cannot be embedded in the piston and reciprocate with it. Overall, this is not a very good picture. You don't really say in words what the difference it; you only show pictures. One of the very important differences, operationally, is that the centrifugal machine provides a continuous flow whereas the reciprocating pump provides a pulsating flow only. There are also major differences in the pressure difference across the pump that the two types can support.
  50. 8 likes
    In practice there is little actual difference in principle operation....they both form a pumping action in order to move a fluid. The pump is generally optimised for minimum compression maximum flow whereas a compressor optimised for maximum compression....sometimes this effectively means minimum flow. (subject to required delta P). Indeed, many are completely interchangeable...for example a high-volume air pump can also be used as a compressor as long as its operational constraints are not exceeded..., most pumps can be used as compressors, with the only penalties being significant efficiency drops due to the optimised design....and of course, in the case of displacement units, the risk of catastrophic failure. It is worth noting though, that liquid fluids are compressible within the strains (no pun intended) of their Bulk Modulus.