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4

According to fan laws, for the fans having constant wheel diameters, the power demand varies

A. Directly as fan speed

B. Square of fan speed

C. Cube of fan speed

D. Square root of fan speed

Correct Answer :

C. Cube of fan speed


Related Questions

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4

Which of the following pump is successfully used for lifting water from deep wells?

A. Centrifugal pump

B. Reciprocating pump

C. Jet pump

D. Air lift pump

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4

Kinematic 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

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4

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

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4

The maximum hydraulic efficiency of an impulse turbine is (where φ = Angle of blade tip at outlet)

A. (1 + cos φ)/2

B. (1 - cos φ)/2

C. (1 + sin φ)/2

D. (1 - sin φ)/2

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4

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 discharge of wheel is

A. 0.25 m3/s

B. 0.5 m3/s

C. 1.5 m3/s

D. 2.5 m3/s

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4

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

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4

Which of the following hydraulic unit is used for transmitting increased or decreased torque to the driven shaft?

A. Hydraulic ram

B. Hydraulic intensifier

C. Hydraulic torque converter

D. Hydraulic accumulator

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4

Low specific speed of a pump implies it is

A. Centrifugal pump

B. Mixed flow pump

C. Axial flow pump

D. None of the above

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4

When a piping system is made up primarily of friction head and very little of vertical lift, then pump characteristics should be

A. Horizontal

B. Nearly horizontal

C. Steep

D. First rise and then fall

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4

The hydraulic 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

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4

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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4

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 + v, v = Velocity of the ship, and V = Velocity of the jet issuing from the ship)

A. waVr /g × (Vr + v)

B. waVr /g × (Vr - v)

C. waVr /g × (Vr + v)²

D. waVr /g × (Vr - v)²

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4

Head developed by a centrifugal pump is

A. Proportional to diameter of impeller

B. Proportional to speed of impeller

C. Proportional to diameter and speed of impeller

D. None of the above

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4

Puck up the wrong statement about centrifugal pump

A. Discharge a diameter

B. Head a speed²

C. Head a diameter

D. Power a speed⁴

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4

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 %

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4

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°

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4

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 glides 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 of the flowing water increases after gliding over the vanes.

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4

A hydraulic accumulator is a device used to store ________ energy which may be supplied to a machine later on.

A. Strain

B. Pressure

C. Kinetic

D. None of these

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4

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 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.

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4

The power developed by a turbine is (where H = Head of water under which the turbine is working)

A. Directly proportional to H1/2

B. Inversely proportional to H1/2

C. Directly proportional to H3/2

D. Inversely proportional to H3/2

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4

In a Francis turbine runner, the numbers of blades are generally between

A. 2 to 4

B. 4 to 8

C. 8 to 16

D. 16 to 24

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4

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

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4

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

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4

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

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4

Maximum impulse will be developed in hydraulic ram when

A. Waste valve closes suddenly

B. Supply pipe is long

C. Supply pipe is short

D. Ram chamber is large

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4

Guide angle as per the aerofoil theory of Kaplan turbine blade design is defined as the angle between

A. Lift and resultant force

B. Drag and resultant force

C. Lift and tangential force

D. Lift and drag

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4

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

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4

Reaction turbines are used for

A. Low head

B. High head

C. High head and low discharge

D. Low head and high discharge

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4

The specific speed of a turbine is given by the equation

A. N√P / H3/2

B. N√P / H²

C. N√P / H5/4

D. N√P / H3

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4

Motion of a liquid in a volute casing of a centrifugal pump is an example of

A. Rotational flow

B. Radial

C. Forced spiral vortex flow

D. Spiral vortex flow