# Hydraulic Machines-Fluid Machineries – Set 07

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## Q1. Low specific speed of turbine implies it is

(A) Propeller turbine
(B) Francis turbine
(C) Impulse turbine
(D) Any one of the above

Answer: (C) Impulse turbine

## Q2. Medium specific speed of turbine implies it is

(A) Propeller turbine
(B) Francis turbine
(C) Impulse turbine
(D) Any one of the above

Answer: (B) Francis turbine

## Q3. Impulse turbine is generally fitted

(A) At the level of tail race
(B) Little above the tail race
(C) Slightly below the tail race
(D) About 2.5 m above the tail race to avoid cavitations

Answer: (B) Little above the tail race

(A) Two
(B) Four
(C) Six
(D) Eight

Answer: (C) Six

## Q5. By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. The saving in case of a double acting reciprocating pump is

(A) 39.2%
(B) 48.8%
(C) 84.8%
(D) 88.4%

Answer: (A) 39.2%

## Q6. The ratio of quantity of liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as

(A) Manometric efficiency
(B) Mechanical efficiency
(C) Overall efficiency
(D) Volumetric efficiency

Answer: (D) Volumetric efficiency

## Q7. A Pelton wheel develops 1750 kW under a head of 100 meters while running at 200 r.p.m. and discharging 2500 liters of water per second. The unit speed of the wheel is

(A) 10 r.p.m.
(B) 20 r.p.m.
(C) 40 r.p.m.
(D) 80 r.p.m.

Answer: (B) 20 r.p.m.

## Q8. Which of the following statement is wrong?

(A) The reaction turbines are used for low head and high discharge
(B) The angle of taper on draft tube is less than 8°
(C) An impulse turbine is generally fitted slightly above the tail race
(D) A Francis turbine is an impulse turbine

Answer: (D) A Francis turbine is an impulse turbine

## Q9. Which of the following pump is successfully used for lifting water to the boilers?

(A) Centrifugal pump
(B) Reciprocating pump
(C) Jet pump
(D) Airlift pump

Answer: (C) Jet pump

## Q10. A turbine develops 10000 kW under a head of 25 meters at 135 r.p.m. Its specific speed is

(A) 175.4 r.p.m.
(B) 215.5 r.p.m.
(C) 241.5 r.p.m.
(D) 275.4 r.p.m

Answer: (C) 241.5 r.p.m.

## Q11. A hydraulic coupling belongs to the category of

(A) Power absorbing machines
(B) Power developing machines
(C) Energy transfer machines
(D) Energy generating machines

Answer: (C) Energy transfer machines

## Q12. 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) None of these

Answer:(B) Mechanical

## Q13. 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

Answer: (D) All of the above

## Q14. A turbine is required to develop 1500 kW at 300 r.p.m. under a head of 150 m. Which of the following turbine should be used?

(A) Pelton wheel with one nozzle
(B) Pelton wheel with two or more nozzles
(C) Kaplan turbine
(D) Francis turbine

Answer: (A) Pelton wheel with one nozzle

## Q15. 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 these

Answer: (B) Difference

## Q16. Pressure intensifier increases the pressure in proportion to

(A) Ratio of diameters
(B) Square of ratio of diameters
(C) Inverse ratio of diameters
(D) Square of inverse ratio of diameters

Answer: (B) Square of ratio of diameters

## Q17. Any change in load is adjusted by adjusting following parameter on turbine

(A) Net head
(B) Absolute velocity
(C) Blade velocity
(D) Flow

Answer: (D) Flow

## Q18. Discharge (Q) of a centrifugal pump is given by (where D = Diameter of impeller at inlet, b = Width of impeller at inlet, and Vf = Velocity of flow at inlet)

(A) Q = π.D.Vf
(B) Q = π.b.Vf
(C) Q = π.D.bf.V
(D) Q = D.b.Vf

Answer: (C) Q = π.D.bf.V

## Q19. Centrifugal pump is started with its delivery valve

(A) Kept fully closed
(B) Kept fully open
(C) Irrespective of any position
(D) Kept 50% open

Answer: (A) Kept fully closed

## Q20. Discharge of a centrifugal pump is

(A) Directly proportional to diameter of its impeller
(B) Inversely proportional to diameter of its impeller
(C) Directly proportional to (diameter)² of its impeller
(D) Inversely proportional to (diameter)² of its impeller

Answer: (D) Inversely proportional to (diameter)² of its impeller

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