# Hydraulic Machines 2

Objective Questions and Answer: Hydraulic Machines 2

Subject:  Hydraulic Machines 2

Part 2: Objective questions and answers of Hydraulic Machines

Q1. Which of the following statement is correct?

a) In an impulse turbine, the water impinges on the buckets with pressure energy.

b) In a reaction turbine, the water guides over the moving vanes with kinetic energy.

c) In an impulse turbine, the pressure of the flowing water remains unchanged and is equal to atmospheric pressure.

d) In a reaction turbine, the pressure, the pressure of the flowing water increases after gliding over the vanes.

Q2. In an inward flow reaction turbine

a) The water flows parallel to the axis of the wheel

b) the water enters at the centre of the wheel and then flows towards the outer periphery of the wheel

c) The water enters the wheel at the outer periphery and then flows towards the centre of the wheel

d) the flow of water is partly radial and partly axial

Q3. In an outward flow reaction turbine

a) The water flows parallel to the axis of the wheel

b) The water enters at the centre of the wheel and then flows towards the outer periphery of the wheel

c) the water enters the wheel at the outer periphery and then flows towards the centre of the wheel

d) The flow of water is partly radial and partly axial

Q4. The hydraulic efficiency of a reaction turbine, is the ratio of

a) Power produced by the turbine to the energy actually supplied by the turbine

b) Actual work available at the turbine to energy imparted to the wheel

c) work-done on the wheel to the energy (or head of water) actually supplied to the turbine

d) none of the above

Q5. The ratio of actual work available at the turbine to the energy imparted to the wheel is

known as ______ efficiency.

a) Hydraulic

b) Mechanical

c) Overall

d) Chemical

Q6. The overall efficiency of a reaction turbine is the ratio of

a) Power produced by the turbine to the energy actually supplied by the turbine

b) work done on the wheel to the energy ( or head of water ) actually supplied to the turbine

c) none of the above

Q7. Which of the following is not a reaction turbine ?

a) Furneyron turbine

b) Jonval turbine

c) Thomson's turbine

d) Pelton wheel

Q8. The Furneyron turbine is ______ reaction turbine

a) an axial flow

b) an inward flow

c) an outward flow

d) a mixed flow

Q10. The Thomson's turbine is ______ reaction turbine.

a) an axial flow

b) an inward flow

c) an outward flow

d) a mixed flow

Q11. The flow ratio of Francis turbine is defined as the ratio of the

a) velocity of flow at inlet to the theoretical jet velocity

b) theoretical velocity of jet to the velocity of flow at inlet

c) velocity of runner at inlet to the velocity of flow at inlet

d) none of the above

Q12. The runaway speed of a hydraulic turbine is the speed

b) at which there will be no damage to the runner

c) corresponding to maximum overload permissible

d) at which the turbine will run freely without load

Q13. The speed of an imaginary turbine, identical with the given turbine, which will develop

a unit power under a unit head, is known as

a) normal speed

b) unit speed

c) specific speed

d) none of these

Q14. The efficiency of a Pelton wheel working under constant head ______ with the increase in power.

a) remains same

b) increases

c) decreases

d) none of the above

Q15. The discharge through a reaction turbine ____ with the increase in unit speed

a) remains same

b) increases

c) decreases

d) none of the above

Q16. The efficiency of a reaction turbine for a given head _____ with the increase in speed.

a) Decreases

b) Increases

c) remains same

d) None of the above

Q17. The cavitation in a hydraulic machine is mainly due to

a) low velocity

b) high velocity

c) low pressure

d) high pressure

Q18. The cavitation in a hydraulic machine

a) causes noise and vibration of various parts

b) reduces the discharge of a turbine

c) causes sudden drop in power output and efficiency

d) all of the above

Q19. The cavitation in reaction turbines is avoided, to a great extent bye

a) Installing the turbine below the tail race level

b) Using stainless steel runner of the turbine

c) providing highly polished blades to the runner

d) all of the above

Q20. The specific speed of a hydraulic turbine depends upon

a) speed and power developed

b) discharge and power developed

c) speed and head of water

d) speed, power developed and head of water

Part 2: Objective questions and answers of Hydraulic Machines