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What is the correct answer?

4

The overall efficiency of the compressed air system is the

A. Ratio of shaft output of the air motor to the shaft input to the compressor

B. Ratio of shaft input to the compressor to the shaft output of air motor

C. Product of shaft output of air motor and shaft input to the compressor

D. None of the above

Correct Answer :

A. Ratio of shaft output of the air motor to the shaft input to the compressor


Related Questions

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4

The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as

A. Compressor efficiency

B. Volumetric efficiency

C. Isothermal efficiency

D. Mechanical efficiency

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4

In a closed cycle gas turbine, the air is compressed

A. Isothermally

B. Polytropically

C. Isentropically

D. None of these

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4

The velocity of air entering in a rocket is ________ as compared to an aircraft.

A. Zero

B. Less

C. More

D. Same

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4

Which of the following statement is correct?

A. The reciprocating compressors are best suited for high pressure and low volume capacity

B. The effect of clearance volume on power consumption is negligible for the same volume of discharge

C. Both (A) and (B)

D. None of these

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4

The ratio of isentropic work to Eulers work is known as

A. Compressor efficiency

B. Isentropic efficiency

C. Euler's efficiency

D. Pressure coefficient

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4

The overall isothermal efficiency of the compressor is defined as the ratio of

A. Work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio

B. Isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor

C. Volume of free air delivery per stroke to the swept volume of the piston

D. Isentropic power to the power required to drive the compressor

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4

In air breathing jet engine, the jet is formed by expanding

A. Highly heated atmospheric air

B. Solids

C. Liquid

D. Plasma

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4

Euler's equation is applicable for

A. Centrifugal compressor

B. Axial compressor

C. Pumps

D. All of the above

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4

1 m of air at atmospheric condition weighs approximately

A. 0.5 kg

B. 1.0 kg

C. 1.3 kg

D. 2.2 kg

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4

The intercooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p₁ = Intake pressure of air, p₂ = Intercooler pressure, and p₃ = Delivery pressure of air)

A. p₂ = p₁ × p₃

B. p₂ = p₁/p₃

C. p₂ = p₁ × p₂

D. p₂ = p₃/p₁

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4

The maximum delivery pressure in a rotary air compressor is

A. 10 bar

B. 20 bar

C. 30 bar

D. 50 bar

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4

If the flow of air through the compressor is perpendicular to its axis, then it is a

A. Reciprocating compressor

B. Centrifugal compressor

C. Axial flow compressor

D. Turbo compressor

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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

Only rocket engines can be propelled to space because

A. They can generate very high thrust

B. They have high propulsion efficiency

C. These engines can work on several fuels

D. They are not air breathing engines

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4

Free air is the air at

A. Atmospheric conditions at any specific location

B. 20°C and 1 kg/cm² and relative humidity of 36%

C. 0°C and standard atmospheric conditions

D. 15°C and 1 kg/cm²

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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

Which of the following statement is correct relating to rocket engines?

A. The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel

B. The stagnation conditions exist at the combustion chamber

C. The exit velocities of exhaust gases are much higher than those in jet engine

D. All of the above

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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

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

In turbo fan engine, the jet velocity as compared to turbojet engine is

A. Less

B. More

C. Same

D. May be less or more depending upon speed

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4

Reciprocating air 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

The capacity of a compressor is expressed in

A. kg/m²

B. kg/m³

C. m³/min

D. m³/kg

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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

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4

The efficiency of roots blower ________ with the increase in pressure ratio.

A. Decreases

B. Increases

C. Does not change

D. None of these

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4

Pick up the false statement

A. Gas turbine is a self starting unit

B. Gas turbine does not require huge quantity of water like steam plant

C. Exhaust losses in gas turbine are high due to large mass flow rate

D. Overall efficiency of gas turbine plant is lower than that of a reciprocating engine

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4

Aeroplanes employ following type of compressor

A. Radial flow

B. Axial flow

C. Centrifugal

D. None of the above

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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

The absolute pressure of air at the outlet of a compressor is called

A. Back pressure

B. Critical pressure

C. Discharge pressure

D. None of these

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4

The thermal efficiency of a gas turbine as compared to a diesel plant is

A. Same

B. More

C. Less

D. Depends on other factors

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4

Cylinder clearance in a compressor should be

A. As large as possible

B. As small as possible

C. About 50% of swept volume

D. About 100% of swept volume