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4

The indicated work per unit mass of air delivered is

A. Directly proportional to clearance volume

B. Greatly affected by clearance volume

C. Not affected by clearance volume

D. Inversely proportional to clearance volume

Correct Answer :

C. Not affected by clearance volume


Related Questions

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4

The mean effective pressure of the compressor is the

A. Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions

B. Volume of air delivered by the compressor

C. Volume of air sucked by the compressor during its suction stroke

D. None of the above

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4

Which is false statement about advantages of multistage compressor in comparison to single stage compressor?

A. Less power requirement

B. Better mechanical balance

C. Less loss of air due to leakage past the cylinder

D. Lower volumetric efficiency

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4

Mechanical efficiency of gas turbines as compared to I.C engines is

A. Higher

B. Lower

C. Same

D. None of the above

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4

There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would

A. Remain same

B. Decrease

C. Increase

D. None of the above

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4

In jet engines, paraffin is usually used as the fuel because of its

A. High calorific value

B. Ease of atomisation

C. Low freezing point

D. Both (A) and (C) above

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4

For supplying intermittent small quantity of air at high pressure, following compressor is best suited

A. Centrifugal

B. Reciprocating

C. Axial

D. Screw

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4

The compressed air may be used

A. In gas turbine plants

B. For operating pneumatic drills

C. In starting and supercharging of I.C. engines

D. All of the above

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4

The ratio of work done per cycle to the swept volume in case of compressor is called

A. Compression index

B. Compression ratio

C. Compressor efficiency

D. Mean effective pressure

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4

What will be the volume of air at 327°C if its volume at 27°C is 1.5 m³/ mt?

A. 3 m³/ mt.

B. 1.5 m³/ mt.

C. 18 m³/ mt.

D. 6 m³/ mt.

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4

Stalling of blades in axial flow compressor is the phenomenon of

A. Air stream blocking the passage

B. Motion of air at sonic velocity

C. Unsteady periodic and reversed flow

D. Air stream not able to follow the blade contour

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4

Gas turbines use following type of air compressor

A. Centrifugal type

B. Reciprocating type

C. Lobe type

D. Axial flow type

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4

Which of the following statement is correct as regard to centrifugal compressors?

A. The flow of air is parallel to the axis of the compressor

B. The static pressure of air in the impeller increases in order to provide centripetal force on the air

C. The impeller rotates at high speeds

D. The maximum efficiency is higher than multistage axial flow compressors

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4

The maximum combustion pressure in gas turbine as compared to I.C. engine is

A. More

B. Less

C. Same

D. Depends on other factors

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4

To avoid moisture troubles, the compressed air main line should

A. Rise gradually towards the point of use

B. Drop gradually towards the point of use

C. Be laid vertically

D. Be laid exactly horizontally

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4

The air entry velocity m a rocket as compared to aircraft is

A. Same

B. More

C. Less

D. Zero

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4

If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix I and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity

A. Vi = Vo

B. Vt > Vo

C. U < Vo

D. V = Uo

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4

Euler's equation can be used for

A. Radial flow compressors

B. Axial flow compressors

C. Pumps

D. All of these

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4

Isothermal compression though most efficient, but is not practicable because

A. It requires very big cylinder

B. It does not increase pressure much

C. It is impossible in practice

D. Compressor has to run at very slow speed to achieve it

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4

Pick up the wrong statement

A. Large gas turbines employ axial flow compressors

B. Axial flow compressors are more stable than centrifugal type compressors but not as efficient

C. Axial flow compressors have high capacity and efficiency

D. Axial flow compressors have instability region of operation

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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

The type of rotary compressor used in aeroplanes, is of

A. Centrifugal type

B. Axial flow type

C. Radial flow type

D. None of these

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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

In the cross compounding of the gas turbine plant

A. H.P. compressor is connected to H.P. turbine and L.P. compressor to L.P. turbine

B. H.P. compressor is connected to L.P. turbine and L.P. compressor is connected to H.P. turbine

C. Both the arrangements can be employed

D. All are connected in series

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4

Reheating in multistage expansion gas turbine results in

A. High thermal efficiency

B. Reduction in compressor work

C. Decrease of heat loss in exhaust

D. Maximum work output

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4

In a high pressure compressor, the delivery pressure is

A. 1 to 5 bar

B. 5 to 8 bar

C. 8 to 10 bar

D. 10 to 15 bar

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4

In jet engines the products of combustion after passing through the gas turbine are discharged into

A. Atmosphere

B. Back to the compressor

C. Discharge nozzle

D. Vacuum

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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

Propulsive efficiency is defined as ratio of

A. Thrust power and fuel energy

B. Engine output and propulsive power

C. Propulsive power and fuel input

D. Thrust power and propulsive power

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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

Water is injected in gas turbine cycle to

A. Control temperature

B. Control output of turbine

C. Control fire hazards

D. Increase efficiency