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What is the correct answer?

4

A centrifugal compressor works on the principle of

A. Conversion of pressure energy into kinetic energy

B. Conversion of kinetic energy into pressure energy

C. Centripetal action

D. Generating pressure directly

Correct Answer :

B. Conversion of kinetic energy into pressure energy


Related Questions

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4

In a centrifugal compressor, the ratio of the ________ to the blade velocity is called slip factor.

A. Inlet whirl velocity

B. Outlet whirl velocity

C. Inlet velocity of flow

D. Outlet velocity of flow

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4

The volume of air delivered in a medium capacity air compressor per unit time is

A. 0.1 to 1.2 m³/s

B. 0.15 to 5 m³/s

C. Above 5 m³/s

D. None of these

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4

The compressor efficiency is the

A. Isothermal H.P/indicated H.R

B. Isothermal H.P./shaft H.R

C. Total output/air input

D. Compression work/motor input

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4

For perfect intercooling in a three stage compressor

A. p₂/p₁ = p₃/p₂ = p₄/p₃

B. p₃/p₁ = p₄/p₂

C. p₁ p₂ = p₃ p₄

D. p₁ p₃ = p₂ p₄

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4

The axial flow compressor is preferred in aircraft gas turbines because of

A. Low frontal area

B. Higher thrust

C. High pressure rise

D. None of these

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4

A closed cycle gas turbine gives ________ efficiency as compared to an open cycle gas turbine.

A. Same

B. Lower

C. Higher

D. None of these

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4

Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on

A. Mass flow rate

B. Pressure ratio

C. Change in load

D. Stagnation pressure at the outlet

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4

The volume of air delivered by the compressor is called

A. Free air delivery

B. Compressor capacity

C. Swept volume

D. None of these

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4

Rotary compressors are suitable for

A. Large discharge at high pressure

B. Low discharge at high pressure

C. Large discharge at low pressure

D. Low discharge at low pressure

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4

A rotary compressor is driven by an

A. Electric motor

B. Engine

C. Either (A) or (B)

D. None of these

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4

The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called

A. Pressure ratio

B. Pressure coefficient

C. Degree of reaction

D. Slip factor

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4

Reheating in gas turbine results in

A. Increase of work ratio

B. Decrease of thermal efficiency

C. Decrease of work ratio

D. Both (A) and (B) above

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4

The minimum work required for a three stage reciprocating air compressor is ________ the work required for each stage.

A. Equal to

B. Double

C. Three times

D. Six times

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4

If p₁ is the pressure of air entering the L.P, cylinder and p₃ is the pressure of air leaving the H.P. cylinder, then the ratio of cylinder diameters for a single acting, two stage reciprocating compressor with complete intercooling is given by

A. D₁/D₂ = (p₁ p₃)1/2

B. D₁/D₂ = (p₁/p₃)1/4

C. D₁/D₂ = (p₁ p₃)1/4

D. D₁/D₂ = (p₃/p₁)1/4

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4

Rotary compressor is best suited for

A. Large quantity of air at high pressure

B. Small quantity of air at high pressure

C. Small quantity of air at low pressure

D. Large quantity of air at low pressure

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4

Gas turbine blades are given a rake

A. Equal to zero

B. In the direction of motion of blades

C. Opposite to the direction of motion of blades

D. Depending on the velocity

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4

A rocket works with maximum overall efficiency when air craft velocity is equal to the

A. Jet velocity

B. Twice the jet velocity

C. Half the jet velocity

D. Average of the jet velocity

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4

The effective power of gas turbines is increased by adding the following in compressor

A. Ammonia and water vapour

B. Carbon dioxide

C. Nitrogen

D. Hydrogen

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4

The ratio of workdone per cycle to the stroke volume of the compressor is known as

A. Compressor capacity

B. Compression ratio

C. Compressor efficiency

D. Mean effective pressure

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4

Propulsion efficiency of the following order is obtained in practice

A. 34 %

B. 50 %

C. 60 %

D. 72 %

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4

The propulsive power of the rocket is (where v₁ = Jet velocity, and v₂ = Aircraft velocity)

A. (v₁² -v₂²)/2g

B. (v₁ - v₂)²/2g

C. (v₁² -v₂²)/g

D. (v₁ - v₂)²/g

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4

The material commonly used for air craft gas turbine is

A. Stainless steel

B. High alloy steel

C. Duralumin

D. Timken, Haste alloys

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4

Volumetric efficiency of a compressor with clearance volume

A. Increases with increase in compression ratio

B. Decreases with increase in compression ratio

C. In not dependent upon compression ratio

D. May increase/decrease depending on compressor capacity

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4

Ratio of compression is the ratio of

A. Gauge discharge pressure to the gauge intake pressure

B. Absolute discharge pressure to the absolute intake pressure

C. Pressures at discharge and suction corresponding to same temperature

D. Stroke volume and clearance volume

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4

Compression efficiency is compared against

A. Ideal compression

B. Adiabatic compression

C. Isentropic compression

D. Isothermal compression

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4

Inter-cooling in multistage compressors is done

A. To cool the air during compression

B. To cool the air at delivery

C. To enable compression in two stages

D. To minimise the work of compression

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4

The process, which causes the air to enter the impeller blades of a centrifugal compressor at ________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.

A. Reduced

B. Increased

C. Zero

D. None of these

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4

The pressure of air at the beginning of the compression stroke is ________ the atmospheric pressure.

A. Equal to

B. Less than

C. More than

D. None of these

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4

A large clearance volume in a reciprocating compressor results in

A. Reduced volume flow rate

B. Increased volume flow rate

C. Lower suction pressure

D. Lower delivery pressure

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4

Axial flow compressor resembles

A. Centrifugal pump

B. Reciprocating pump

C. Turbine

D. Sliding vane compressor