# Hydraulic Machines Questions and Answers – Design of Pelton Wheel

This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses 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

Explanation: 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

Explanation: 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

Explanation: 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

Explanation: 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

Explanation: Expression for jet ratio is m=D/d which is 10*0.125= 1.25 meters.
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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

Explanation: 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

Explanation: 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

Explanation: 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

Explanation: 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

Explanation: The expression for measuring width of buckets is 5*diameter of jet, which is 5*85=425mm.

11. If diameter of jet is 85mm and diameter of runner is 1.5 meter then depth of buckets is ___________
a) 100mm
b) 105mm
c) 106mm
d) 102mm

Explanation: The expression for measuring depth of buckets is 1.2*diameter of jet, which is 1.2*85=102mm.

12. If diameter of jet is 85mm and diameter of runner is 1.5 meter then calculate number of buckets on Pelton wheel approximately
a) 20
b) 22
c) 23
d) 25

Explanation: The expression for measuring number of buckets is 15 + diameter of runner/2 time’s diameter of jet, which are 15 + 1.5/2*0.085.

13. The width of Pelton wheel should be 5 times the diameter of jet?
a) True
b) False

Explanation: To obtain Pelton wheel of higher efficiency, width of buckets is specified as 5 times diameter of jet by considering several experimental observations.

14. The ratio of diameter of jet to diameter of runner is _____________
a) 1:3
b) 1:6
c) 1:5
d) 3:4

Explanation: To obtain Pelton wheel of higher efficiency, diameter of runner is 5 times diameter of jet by considering several experimental observations.

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