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4

According to fan laws, for fans having constant wheel diameter, the pressure varies

A. Directly as fan speed

B. Square of fan speed

C. Cube of fan speed

D. Square root of fan speed

Correct Answer :

B. Square of fan speed


Related Questions

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4

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

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4

The efficiency of jet propulsion for a ship with inlet orifices at right angles to the direction of motion of ship is given by

A. [2(Vr - v) v]/ Vr²

B. 2(Vr + v) v]/ Vr²

C. [(Vr - v) v]/ Vr

D. [(Vr + v) v]/ Vr

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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

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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

For 450 m head of water, _________ shall be used.

A. Pelton wheel

B. Kaplan turbine

C. Francis turbine

D. None of these

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4

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

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4

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

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4

The impeller of a centrifugal pump may have

A. Volute casing

B. Volute casing with guide blades

C. Vortex casing

D. Any one of these

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4

The maximum number of jets generally employed in impulse turbine without jet interference is

A. 4

B. 6

C. 8

D. 12

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4

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

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4

In axial flow fans and turbines, fluid enters and leaves as follows

A. Radially, axially

B. Axially, radially

C. Axially, axially

D. Radially, radially

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4

Low specific speed of turbine implies it is

A. Propeller turbine

B. Francis turbine

C. Impulse turbine

D. Any one of the above

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4

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

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4

The relation between hydraulic efficiency (ηh), mechanical efficiency (ηm) and overall efficiency (ηo) is

A. ηh = ηo × ηm

B. ηm = ηm × ηh

C. ηo = ηh × ηm

D. None of these

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4

A jet of water is striking at the centre of a curved vane moving with a 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

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4

In a reciprocating pump, air vessels are used to

A. Smoothen the flow

B. Reduce suction head

C. Increase delivery head

D. Reduce acceleration head

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4

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 %

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4

For very high discharge at low pressure such as for flood control and irrigation applications, following type of pump is preferred

A. Centrifugal

B. Axial flow

C. Reciprocating

D. Mixed flow

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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

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

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4

A turbine pump is basically a centrifugal pump equipped additionally with

A. Adjustable blades

B. Backward curved blades

C. Vaned diffusion casing

D. Inlet guide blades

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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

In a centrifugal pump casing, the flow of water leaving the impeller, is

A. Rectilinear flow

B. Radial flow

C. Free vortex motion

D. Forced vortex

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4

In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by

A. Designing new impeller

B. Trimming the impeller size to the required size by machining

C. Not possible

D. Some other alterations in the impeller

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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

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

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. waV/2g × sinθ

B. waV/g × sinθ

C. waV²/2g × sin2θ

D. waV²/g × sinθ

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4

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

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4

If the ratio's of the corresponding forces acting at corresponding points are equal, then the model and the prototype are said to have.

A. Geometric similarity

B. Kinematic similarity

C. Dynamic similarity

D. None of these

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4

Air vessels in reciprocating pump are used to

A. Smoothen flow

B. Reduce acceleration to minimum

C. Increase pump efficiency

D. Save pump from cavitations