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4

An ideal air compressor cycle without clearance on PV diagram can be represented by following processes

A. One adiabatic, two isobaric, and one constant volume

B. Two adiabatic and two isobaric

C. Two adiabatic, one isobaric and one constant volume

D. One adiabatic, one isobaric and two constant volumes

Correct Answer :

A. One adiabatic, two isobaric, and one constant volume


Related Questions

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4

Pick up the wrong statement

A. Centrifugal compressors deliver practically constant pressure over a considerable range of capacities

B. Axial flow compressors have a substantially constant delivery at variable pressures

C. Centrifugal compressors have a wider stable operating range than axial flow compressors

D. Axial flow compressors are bigger in diameter compared to centrifugal type

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4

In a jet propulsion

A. The propulsive matter is ejected from within the propelled body

B. The propulsive matter is caused to flow around the propelled body

C. Its functioning does not depend upon presence of air

D. None of the above

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4

In a turbo jet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in

A. Exit nozzle, which is a constant volume process

B. Exit nozzle, which is essentially an isentropic process

C. Turbine blades, which is a constant volume process

D. Turbine blades, which is essentially an isentropic process

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4

Air-fuel ratio in a jet engine will be of the order of

A. 10 : 1

B. 15 : 1

C. 20 : 1

D. 60 : 1

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4

In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in ________ of the piston.

A. One stroke

B. Two strokes

C. Three strokes

D. Four strokes

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4

As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio

A. Increases

B. Decreases

C. Remain same

D. First increases and then decreases

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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

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

The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the

A. Rotor to static enthalpy rise in the stator

B. Stator to static enthalpy rise in the rotor

C. Rotor to static enthalpy rise in the stage

D. Stator to static enthalpy rise in the stage

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4

In gas turbines, high thermal efficiency is obtained in

A. Closed cycle

B. Open cycle

C. Both of the above

D. Closed/open depending on other considerations

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4

The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is

A. Heated

B. Compressed air before entering the combustion chamber is heated

C. Bled gas from turbine is heated and readmitted for complete expansion

D. Exhaust gases drive the compressor

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4

During base load operation, the best method of controlling compressor is

A. Start-stop motor

B. Constant speed unloader

C. Relief valve

D. Variable speed

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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

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 jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of

A. Vacuum

B. Atmospheric air

C. Compressed air

D. Oxygen alone

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4

The advantage of multistage compression over single stage compression is

A. Lower power consumption per unit of air delivered

B. Higher volumetric efficiency

C. Decreased discharge temperature

D. All of the above

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4

Axial flow compressor has the following advantage over centrifugal compressor

A. Larger air handling ability per unit frontal area

B. Higher pressure ratio per stage

C. Aerofoil blades are used

D. Higher average velocities

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4

Pick up the wrong statement

A. Pulsejet requires no ambient air for propulsion

B. Ramjet engine has no turbine

C. Turbine drives compressor in a Turbojet

D. Bypass turbojet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

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4

Pressure ratio in gas turbines is the ratio of

A. Compressor pressure ratio

B. Highest pressure to exhaust pressure

C. Inlet pressure to exhaust pressure

D. Pressures across the turbine

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4

Pick up the correct statement

A. Gas turbine uses low air-fuel ratio to economise on fuel

B. Gas turbine uses high air-fuel ratio to reduce outgoing temperature

C. Gas turbine uses low air-fuel ratio to develop the high thrust required

D. All of the above

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4

The pressure and temperature conditions of air at the suction of compressor are

A. Atmospheric

B. Slightly more than atmospheric

C. Slightly less than atmospheric

D. Pressure slightly less than atmospheric and temperature slightly more than atmospheric

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4

Separators are generally used in air compressor installations

A. Before the intercooler

B. After the intercooler

C. Between the aftercooler and receiver

D. Before first stage suction

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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 type of rotary compressor used in gas turbines, is of

A. Centrifugal type

B. Axial flow type

C. Radial flow type

D. None of these

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4

Choose the correct statement

A. Gas turbine requires lot of cooling water

B. Gas turbine is capable of rapid start up and loading

C. Gas turbines has flat efficiency at part loads

D. Gas turbines have high standby losses and require lot of maintenance

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4

For maximum work, the reheating should be done to an intermediate pressure of (Where p₁ = Maximum pressure, and p₂ = Minimum pressure)

A. (p₁ - p₂)/2

B. (p₁ + p₂)/2

C. p₁/p₂

D. p₁ p₂

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4

A rocket engine uses ________ for the combustion of its fuel.

A. Surrounding air

B. Compressed atmospheric air

C. Its own oxygen

D. None of these

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4

The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turbine and fixed higher and lower temperature) with increase in pressure ratio will

A. Increase first at fast rate and then slow

B. Increase first at slow rate and then fast

C. Decrease continuously

D. First increase, reach maximum and then decrease

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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

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