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Slip in the case of a centrifugal pump

1

Increases the flow rate

2

Reduces the energy transfer

3

Reduces the speed

4

Increase cavitation

Solution:

Air vessel in a reciprocating pump is used

1

To reduce suction head

2

To reduce suction head

3

To increase delivery head

4

To obtain continuous supply of the water at uniform rate

Solution:

A minimum Net Positive Suction Head (NPSH) is required for a hydraulic pump to

1

increase the delivery head

2

increase the suction head

3

prevent the cavitation

4

increase the efficiency

Solution:

The unit power of the reaction turbine

1

Increases with the unit speed

2

Decreases with the unit speed

3

Decreases and increases with the unit speed

4

Increases and decreases with the unit speed

Solution:

A centrifugal pump driven by a directly coupled 3 kW motor of 1450 rpm speed is proposed to be connected to another motor of 2900 rpm. The power of the motor should be

1

24 kW

2

18 W

3

12 kW

4

6 kW

Solution:

The net positive suction head is

1

pressure head + kinetic head

2

pressure head + vapour pressure + kinetic head

3

pressure head - vapour pressure + kinetic head

4

pressure head - vapour pressure - kinetic head

Solution:

Cavitation depends upon

1

vapour pressure which is function of temperature

2

absolute pressure or barometric pressure

3

suction pressure (Hs) which is height of runner outlet above tail race level.

4

all the above

Solution:

The specific speed of hydraulic pumps is the speed of a geometrically similar pump working against a unit head and

1

Delivering unit quantity of water

2

Consuming unit power

3

Having unit velocity of flow

4

Having unit radial velocity

Solution:

The specific speed of a hydraulic pump is the speed of a geometrically similar pump working against a unit head and

1

consuming unit power

2

delivering a unit quantity of water

3

having unit velocity of flow

4

having a unit radial velocity

Solution:

A centrifugal pump has an impellor with an outer diameter of 30 cm. Water enters the impellor radially. Vane tips are radial at the outlet. The rotative speed is 1500 rpm and the manometry efficiency is 80%. What is the net head developed (in meters)? [Assuming acceleration due to gravity = g = π]

1

45

2

60

3

70

4

100

Fluid-mechanics Questions Set 73:

Slip in the case of a centrifugal pump

Solution:

Air vessel in a reciprocating pump is used

Solution:

A minimum Net Positive Suction Head (NPSH) is required for a hydraulic pump to

Solution:

The unit power of the reaction turbine

Solution:

A centrifugal pump driven by a directly coupled 3 kW motor of 1450 rpm speed is proposed to be connected to another motor of 2900 rpm. The power of the motor should be

Solution:

The net positive suction head is

Solution:

Cavitation depends upon

Solution:

The specific speed of hydraulic pumps is the speed of a geometrically similar pump working against a unit head and

Solution:

The specific speed of a hydraulic pump is the speed of a geometrically similar pump working against a unit head and

Solution:

A centrifugal pump has an impellor with an outer diameter of 30 cm. Water enters the impellor radially. Vane tips are radial at the outlet. The rotative speed is 1500 rpm and the manometry efficiency is 80%. What is the net head developed (in meters)? [Assuming acceleration due to gravity = g = π]

Solution:

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