# Hydraulic Machines 3

Objective Questions and Answer: Hydraulic Machines 3

Subject:  Hydraulic Machines 3

Part 3: Objective questions and answers of Hydraulic Machines

Q1. A jet of water is striking at the centre of a curved vane moving with uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is ______ of the jet velocity.

a) One Half

b) One third

c) Two third

d) Three fourth

Q2. The maximum efficiency of jet propulsion of a ship with inlet orifices at right angles to the direction of motion of ship, is

a) 40 %

b) 50 %

c) 60 %

d) 80%

Q3. The undershot water wheels are those in which

a) The wheel runs entirely by the weight of water

b) The wheel runs entirely by the impulse of water

c) The wheel runs partly by the weight of water and partly by the impulse of water

d) None of the above

Q4. Which of the following statement is correct as regard to water wheels ?

a) They have slow speeds

b) They are suitable even for low water heads

c) They give constant efficiency, even if the discharge is not constant

d) All of the above

Q5. Braking jet in an impulse turbine is used

a) To break the jet of water

b) To bring the runner to rest in a short time

c) To change the direction of runner

d) None of these

Q6. A Pelton wheel is

a) Tangential flow impulse turbine

b) Inward flow impulse turbine

c) Outward flow impulse turbine

d) Inward flow reaction turbine

Q7. An impulse turbine is used for

d) High discharge

Q8. The gross or total head of the turbine is the ______ of the water levels at the head race and tail race.

a) Sum

b) Difference

c) Product

d) None of the above

Q9. The hydraulic efficiency of an impulse turbine is the

a) Ratio of the actual power produced by the turbine to the energy actually supplied by the turbine

b) Ratio of the actual work available at the turbine to the energy imparted to the wheel

c) Ratio of the work done on the wheel to the energy of the jet

d) None of the above

Q10. The mechanical efficiency of an impulse turbine is

a) Ratio of the actual power produced by the turbine to the energy actually supplied by the turbine

b) Ratio of the actual work available at the turbine to the energy imparted to the wheel

c) Ratio of the work done on the wheel to the energy of the jet

d) None of the above

Q11. The overall efficiency of an impulse turbine is maximum when velocity of wheel is ______ of the jet velocity.

a) One fourth

b) One half

c) Three fourth

d) Double

Q12. The overall efficiency for a Pelton wheel lies between

a) 0.5 to 0.65

b) 0.65 to 0.75

c) 0.75 to 0.85

d) 0.85 to 0.90

Q13. A double overhung Pelton wheel has

a) Two jets

b) Two runners

c) Four jets

d) Four runners

Q14. The width of the bucket for a Pelton wheel is generally ______ the diameter of jet.

a) Double

b) Three times

c) Four times

d) Five times

Q15. The depth of the bucket for a Pelton wheel is generally ______ the diameter of Jet.

a) Equal to

b) 1.2 times

c) 1.8 times

d) Double

Q16. The jet ratio is defined as the ratio of the

a) Diameter of jet to the diameter of Pelton wheel

b) Velocity of jet to the velocity of Pelton wheel

c) Diameter of Pelton wheel to the diameter of jet

d) Velocity of Pelton wheel to the velocity of jet

Q17. Which of the following is not an impulse turbine ?

b) Turgo turbine

c) Pelton wheel

d) Kaplan turbine

Q18. The maximum number of jets, generally, employed in an impulse turbine without jet interference are

a) Two

b) Four

c) Six

d) Eight

Q19. The function of guide vanes in a reaction turbine is to

a) Allow the water to enter the runner without shock

b) Allow the water to flow over them, without forming eddies

c) Allow the required quantity of water to enter the turbine

d) All of the above

Q20. In a reaction turbine, the draft tube is used

a) To run the turbine full

b) To prevent air to enter the turbine

c) To increase the head of water by an amount equal to the height of the runner outlet above the tail race

d) To transport water to downstream

Part 3: Objective questions and answers of Hydraulic Machines