Hydraulic Machines Multiple Choice Questions on “Design of Pelton Wheel”.
1. Design of Pelton wheel means the following data is to be determined.
a) Width of buckets
b) Depth of buckets
c) Number of buckets
d) All of the mentioned
Answer: d
Clarification: In design of Pelton wheel we determine diameter of jet, diameter of runner, Width of buckets, Depth of buckets, Number of buckets on runner.
2. The width of buckets of Pelton wheel is _________________
a) 2 times diameter of jet
b) 3 times diameter of jet
c) 4 times diameter of jet
d) 5 times diameter of jet
Answer: d
Clarification: To obtain Pelton wheel of higher efficiency, width of buckets is specified as 5 times diameter of jet by considering several experimental observations.
3. The depth of buckets of Pelton wheel ____________
a) 1.2 times diameter of jet
b) 1.3 times diameter of jet
c) 1.4 times diameter of jet
d) 1.5 times diameter of jet
Answer: a
Clarification: To obtain Pelton wheel of higher efficiency, depth of buckets is specified as 1.2 times diameter of jet by considering several experimental observations.
4. The ratio of pitch diameter of Pelton wheel to diameter of jet is known as ___________
a) Speed ratio
b) Jet ratio
c) Velocity ratio
d) Co-efficient of velocity
Answer: b
Clarification: The ratio of pitch diameter of Pelton wheel to diameter of jet is known as jet ratio.
5. Find the diameter of jet D, if jet ratio m and diameter of jet d are given as 10 and 125mm.
a) 1.25 meters
b) 1.5 meters
c) 2 meters
d) 1.2 meters
Answer: a
Clarification: Expression for jet ratio is m=D/d which is 10*0.125= 1.25 meters.
6. The number of buckets of Pelton wheel is 25 and diameter of runner is 1.5meters then calculate diameter of jet is ___________
a) 80mm
b) 85mm
c) 90mm
d) 82mm
Answer: b
Clarification: The expression for measuring number of buckets is 15 + diameter of runner/2 times diameter of jet by using this expression we get diameter of jet as 85mm.
7. In most of cases the value of jet ratio is _______________
a) 10
b) 11
c) 12
d) 13
Answer: c
Clarification: Jet ratio is 12 because in most of Pelton turbines diameter of runner is 12 times the diameter of jet.
8. Number of buckets on runner of Pelton wheel is given by expression? (D-diameter of runner and d- diameter of jet)
a) 15 + D/2d
b) 15 + 3D/2d
c) 15 + D/d
d) 15 + 2D/d
Answer: a
Clarification: To obtain Pelton wheel of higher efficiency, number of buckets is specified as 15 + D/2d by considering several experimental observations.
9. ____________ is obtained by dividing total rate of flow through the turbine by rate of flow through single jet.
a) Number of jets
b) Diameter of jets
c) Velocity of jets
d) Speed ratio
Answer: a
Clarification: Total discharge is sum of individual discharges hence, by dividing total rate of flow through the turbine by rate of flow through single jet we get number of jets.
10. If diameter of jet is 85mm and diameter of runner is 1.5 meter then calculate width of buckets.
a) 400mm
b) 500mm
c) 420mm
d) 425mm