FUTURE ADVANCEMENT IN PELTON WHEEL TURBINE
The most common problem in the Pelton wheel turbine of most of the laboratories functioning is the problem in corrosion and problem in its repair during its breakdown due to its bulky nature. Common solutions for the above mentioned problems are:
· Routine maintenance of Pelton wheel turbine
· Careful handling of the Pelton wheel test rig
· Keeping its parts lubricated regularly
· Replacement of ineffective parts
However there have been no permanent solutions given to such kinds of problem.
So keeping in mind the inefficiency such problems cause, we have proposed a model wherein a flange with bearing is attached for rotational motion of the suction pipe.
The suction pipe of Pelton wheel is constantly submerged in water which moreover increases the corrosion of the pipe. So the rotational motion of the pipe helps to lift the pipe and keep it away from water thus helping the pipe from getting corroded.
The detail of the proposed model is given further. This model eliminates the cost incurred due to routine maintenance work, replacement of entire pipe and repairs.
Thus this model will be helpful in the increased efficiency of Pelton wheel test rig in the laboratories.
We have also discussed about the alternative methods that can be used which are readily available in market for construction of the basic concept of the proposed model.
5.2 Design of flange:
A: Hub dimensions:
Internal diameter of hub (d) = 120mm
Outer diameter of hub (D) = 150mm
Length of hub (l) = 0.5 (d)
B: Flange dimensions:
Outer diameter of flange (D3) = 250mm
Thickness of flange (t) = 0.2*(d)
= 25 mm
C: Bolt dimensions:
Bolt circle diameter (D2) = 210 mm
Diameter of hole for bolts (d2) = 18 mm
5.3 Design of bearing:
A bush bearing is used between the two pipes in order to have motion of the inner pipe. The bush is made of Bronze.
The design of bearing is as follows:
Load (F) = 20 kN
Speed (N) = 60 rpm
Wear (w) = 0.03 mm
Life (t) = 500 h
From the table 5.1,
pmax = 25 MPa
vmax = 0.3 m/s
pvmax = 1.636 MPa ms-1
From the SKF manufacturers catalogue (table 5.2),
Inner diameter = 45 mm
Outer diameter = 55 mm
Length of bush = 80 mm
We know that,
p = F/dl = (20 x 103)/(45 x 80) = 5.55 MPa
since 5.55 < 25 MPa, hence it is safe.
v = π d N = (π x 45x 10 -3 x 60) / 60 = 0.282 m/s
since 0.282 < 0.3 m/s, hence it is safe.
pv = 5.55 x 0.28 = 1.554 MPa.ms-1
1.554 < 1.636 MPa.ms-1, hence the design is safe.
Checking for wear,
w = K x p x v x t = 30 x 10-6 x 5.55 x 0.282 x 500 =0.0234 mm.
Hence, the design of bearing is safe
5.6 Other alternatives:
Comparison of Flexible coupling and the stainless steel flexible pipe connector:
In the market for achieving the transverse motion of the pipe we have stainless steel flexible pipe connector as shown in the figure.
The cost of this stainless steel pipe connector is 157$ of 12 inch which is equal to rs.7850 which is very costly. So we have manufactured a localized flexible coupling whose cost is around rs.2040 which is very much cheap than what is available in the market. The approximate life of our coupling is around 3-4 years if kept in a good condition.