4

0.26

0.36

0.46

0.56

C. 0.46

4

# In order to avoid cavitation in centrifugal pumps

The suction pressure should be high

The delivery pressure should be high

The suction pressure should be low

The delivery pressure should be low

4

# Low specific speed of turbine implies it is

Propeller turbine

Francis turbine

Impulse turbine

Any one of the above

4

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

Slow speed with radial flow at outlet

Medium speed with radial flow at outlet

High speed with radial flow at outlet

High speed with axial flow at outlet

4

Casing

Delivery pipe

Suction pipe

Impeller

4

Volute casing

Vortex casing

Any one of these

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)

waVr /g × (Vr + v)

waVr /g × (Vr - v)

waVr /g × (Vr + v)²

waVr /g × (Vr - v)²

4

# Puck up the wrong statement about centrifugal pump

Discharge a diameter

Power a speed⁴

4

Axially, axially

4

Axial

Centrifugal

Vortex

4

# According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies

Directly as fan speed

Square of fan speed

Cube of fan speed

Square root of fan speed

4

[wa (V - v)]/2g

[wa (V - v)]/g

[wa (V - v)²]/2g

[wa (V - v²)]/g

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.

Geometric similarity

Kinematic similarity

Dynamic similarity

None of these

4

# The flow ratio of Francis turbine is defined as the ratio of the

Velocity of flow at inlet to the theoretical jet velocity

Theoretical velocity of jet to the velocity of flow at inlet

Velocity of runner at inlet to the velocity of flow at inlet

None of the above

4

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

Directly proportional to H1/2

Inversely proportional to H1/2

Directly proportional to H3/2

Inversely proportional to H3/2

4

# The cavitation in reaction turbines is avoided, to a great extent by

Installing the turbine below the tail race level

Using stainless steel runner of the turbine

Providing highly polished blades to the runner

All of the above

4

# The specific speed of a turbine is the speed of an imaginary turbine, identical with the given turbine, which

Delivers unit discharge under unit head

Delivers unit discharge under unit speed

Develops unit power under unit head

Develops unit power under unit speed

4

39.2 %

48.8 %

84.8 %

88.4 %

4

One-fourth

One-half

Three-fourth

Double

4

10° to 15°

15° to 20°

20° to 25°

25° to 30°

4

# The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is

Slow speed with radial flow at outlet

Medium speed with radial flow at outlet

High speed with radial flow at outlet

High speed with mixed flow at outlet

4

# The specific speed of turbine is defined as the speed of a unit

Of such a size that it delivers unit discharge at unit head

Of such a size that it delivers unit discharge at unit power

Of such a size that it requires unit power per unit head

Of such a size that it produces unit horse power with unit head

4

# Impulse turbine is generally fitted

At the level of tail race

Little above the tail race

Slightly below the tail race

About 2.5 m above the tail race to avoid cavitations.

4

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

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

Workdone per kN of water Losses within the impeller

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

All of the above

4

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

Centrifugal pump

Reciprocating pump

Jet pump

Airlift pump

4

# Delivery head of a centrifugal pump is

Directly proportional to N

Inversely proportional to N

Directly proportional to N²

Inversely proportional to N²

4

# Which of the following is not a reaction turbine?

Fourneyron turbine

Journal turbine

Thomson's turbine

Pelton wheel

4

# Medium specific speed of a pump implies it is

Centrifugal pump

Mixed flow pump

Axial flow pump

Any one of the above

4

(1 + cos φ)/2

(1 - cos φ)/2

(1 + sin φ)/2

(1 - sin φ)/2

4

# Mechanical efficiency of a centrifugal pump is the ratio of

Energy available at the impeller to the energy supplied to the pump by the prime mover

Actual workdone by the pump to the energy supplied to the pump by the prime mover

Energy supplied to the pump to the energy available at the impeller

Manometric head to the energy supplied by the impeller per kN of water