Hydraulic Machines

Q1: The force exerted by a jet of water (in a direction normal to flow) impinging on a fixed plate inclined at an angle θ with the jet is

A

B

C

D

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: Which of the following turbine is preferred for 0 to 25 m head of water?

A Pelton wheel

B Kaplan turbine

C Francis turbine

D none of these

Q4: For centrifugal pump impeller, the maximum value of the vane exit angle is

A 10° to 15°

B 15° to 20°

C 20° to 25°

D 25° to 30°

Q5: Work done by a turbine __________ upon the weight of water flowing per second.

A depends

B does not depend

Q6: Which of the following pump is preferred for flood control and irrigation applications?

A Centrifugal pump

B Axial flow pump

C Mixed flow pump

D Reciprocating pump

Q7: The principle of jet propulsion is used in driving the ships and aeroplanes.

A Correct

B Incorrect

Q8: In an impulse turbine, the jet of water impinges on the bucket with a low velocity and after flowing over the vanes, leaves with a high velocity.

A True

B False

Q9: The power produced by the reaction turbine is __________ to the head of water.

A directly proportional

B inversely proportional

Q10: 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

Q11: 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

Q12: The overshot water wheels are those in which the wheel runs entirely by the __________ of water.

A weight

B impulse

Q13: Manometric head, in case of a centrifugal pump, is equal to

A Suction lift + Loss of head in suction pipe due to friction + Delivery lift + Loss of head in delivery pipe due to friction + Velocity head in the delivery pipe

B Workdone per kN of water - Losses within the impeller

C Energy per kN at outlet of impeller - Energy per kN at inlet of impeller

D all of the above

Q14: If Hg is the gross or total head and hf is the head lost due to friction, then net or effective head (H) is given by

A H = Hg/hf

B H = Hg x hf

C H = Hg + hf

D H = Hg - hf

Q15: 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

Q16: The static head of a centrifugal pump is equal to the __________ of suction head and delivery head.

A product

B difference

C sum

Q17: Power required to drive a centrifugal pump is directly proportional to __________ of its impeller.

A diameter

B square of diameter

C cube of diameter

D fourth power of diameter

Q18: A ship with jet propulsion draws water through inlet orifices at right angles to the direction of its motion. The propelling force of the jet is (where a = Area of the jet, Vr = Relative velocity of the jet and ship = V + vv = Velocity of the ship, and V = Velocity of the jet issuing from the ship)

A

B

C

D

Q19: The efficiency of a Pelton wheel working under constant head __________ with the increase in power.

A remains same

B increases

C decreases

Q20: Theoretical power required (in watts) to drive a reciprocating pump is (where w = Specific weight of liquid to be pumped in N/m3Q = Discharge of the pump in m3/s, Hs = Suction head in metres, and Hd = Delivery head in metres)

A wQHs

B wQHd

C wQ(Hs - Hd)

D wQ(Hs + Hd)

Q21: A Francis turbine is used when the available head of water is

A 0 to 25 m

B 25 m to 250 m

C above 250 m

D none of these

Q22: 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

Q23: The maximum number of jets, generally, employed in an impulse turbine without jet interference are

A two

B four

C six

D eight

Q24: Geometric similarity is said to exist between the model and the prototype, if both of them

A have identical velocities

B are equal in size and shape

C are identical in shape, but differ only in size

D have identical forces

Q25: When the speed of the pump increases, its net positive suction head (NPSH) requirement decreases.

A Agree

B Disagree

Q26: The speed ratio of a Francis turbine is defined as the ratio of the theoretical jet velocity to the peripheral speed at inlet.

A Yes

B No

Q27: A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit power of the wheel is

A 0.25 kW

B 0.75 kW

C 1.75 kW

D 3.75 kW

Q28: The unit discharge through the turbine is

A

B

C

D

Q29: Multi-stage centrifugal pumps are used to

A give high discharge

B produce high heads

C pump viscous fluids

D all of these

Q30: A hydraulic coupling belongs to the category of

A power absorbing machines

B power developing machines

C energy transfer machines

D energy generating machines

Q31: The capacity of a hydraulic accumulator is generally specified as the maximum amount of energy stored.

A True

B False

Q32: The breast water wheels are those in which the wheel runs partly by the weight of water and partly by the impulse of water.

A True

B False

Q33: The specific speed from 160 to 500 r.p.m. of a centrifugal pump indicates that the pump is

A slow speed with radial flow at outlet

B medium speed with radial flow at outlet

C high speed with radial flow at outlet

D high speed with axial flow at outlet

Q34: The discharge of a centrifugal pump working under constant head __________ with the speed.

A increases

B decreases

Q35: 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.b.Vf

D Q = D.b.Vf

Q36: Discharge of a centrifugal pump is (where N = Speed of the pump impeller)

A directly proportional to N

B inversely proportional to N

C directly proportional to N2

D inversely proportional to N2

Q37: In a reaction turbine, the pressure head of water, while flowing over the vanes, is converted into kinetic head before leaving the wheel.

A Agree

B Disagree

Q38: 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 actual work available at the turbine to the energy imparted to the wheel

C workdone on the wheel to the energy (or head of water) actually supplied to the turbine

D none of the above

Q39: The efficiency of a centrifugal pump will be maximum when the blades are bent backward.

A Yes

B No

Q40: Delivery head of water of a centrifugal pump is inversely proportional to diameter of its impeller.

A Yes

B No

Q41: The specific speed of a centrifugal pump, delivering 750 litres of water per second against a head of 15 metres at 725 r.p.m., is

A 24.8 r.p.m.

B 48.2 r.p.m

C 82.4 r.p.m.

D 248 r.p.m

Q42: In the casing of a centrifugal pump, the kinetic energy of the water is converted into pressure energy before the water leaves the casing.

A True

B False

Q43: A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the

A kinetic head

B velocity head

C manometric head

D static head

Q44: The discharge of a double acting reciprocating pump is (where L = Length of stroke, A = Cross-sectional area of piston, and N = Speed of crank in r.p.m.)

A L.A.N

BL.A.N

C

D

Q45: Slip of a reciprocating pump is defined as the

A ratio of actual discharge to the theoretical discharge

B sum of actual discharge and the theoretical discharge

C difference of theoretical discharge and the actual discharge

D product of theoretical discharge and the actual discharge

Q46: The speed of a turbine runner is

A directly proportional to H1/2

B inversely proportional to H1/2

C directly proportional to H3/2

D inversely proportional to H3/2

Q47: In a reciprocating pump, air vessels are fitted to the suction pipe and delivery pipe close to the cylinder of the pump.

A True

B False

Q48: For centrifugal pump impeller, the maximum value of the vane exit angle is

A 10° to 15°

B 15° to 20°

C 20° to 25°

D 25° to 30°

Q49: In a Kaplan turbine runner, the number of blades are generally between

A 2 to 4

B 4 to 8

C 8 to l6

D 16 to 24

Q50: 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

Q51: 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


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