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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

Correct Answer :

B. Axial flow type


Related Questions

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4

Pick up the correct statement

A. Closed cycle gas turbine is an I.C engine

B. Gas turbine uses same working fluid over and over again

C. Ideal efficiency of closed cycle gas turbine plant is more than Carnot cycle efficiency

D. Thrust in turbojet is produced by nozzle exit gases.

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4

The compressor capacity is defined as 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

An air compressor may be controlled by

A. Throttle control

B. Clearance control

C. Blow off control

D. Any one of the above

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4

Reheating in a multistage expansion gas turbine __________ compressor work.

A. Has no effect on

B. Decreases

C. Increases

D. None of these

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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 temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.

A. Equal to

B. Less than

C. More than

D. None of these

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4

In a jet engine, the air-fuel ratio is

A. 30 : 1

B. 40 : 1

C. 50 : 1

D. 60 : 1

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4

The main purpose of reheating in gas turbine is to

A. Increase temperature

B. Reduce turbine size

C. Increase power output

D. Increase speed

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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

The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation

A. 0.1 %

B. 0.5 %

C. 1.0 %

D. 5 %

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4

Which of the following plants is smallest and lightest for generating a given amount of power?

A. Gas turbine plant

B. Petrol engine

C. Diesel engine

D. Solar plant

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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

The net work input required for compressor with increase in clearance volume

A. Increases

B. Decreases

C. Remains same

D. Increases/decreases depending on compressor capacity

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4

In the axial flow gas turbine, the work ratio is the ratio of

A. Compressor work and turbine work

B. Output and input

C. Actual total head temperature drop to the isentropic total head drop from total head inlet to static head outlet

D. Actual compressor work and theoretical compressor work

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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 minimum work in multistage compression, assuming same index of compression in all stages

A. Work done in first stage should be more

B. Work done in subsequent stages should increase

C. Work done in subsequent stages should decrease

D. Work done in all stages should be equal

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4

In a centrifugal compressor, an increase in speed at a given pressure ratio causes

A. Increase in flow

B. Decrease in flow

C. Increase in efficiency

D. Increase in flow and decrease in efficiency

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4

The ratio of isentropic work to Euler work is known as

A. Pressure coefficient

B. Work coefficient

C. Polytropic reaction

D. Slip factor

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4

Which of the following fuels can be used in turbojet engines?

A. Liquid hydrogen

B. High speed diesel oil

C. Kerosene

D. Methyl alcohol

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4

In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of workdone on the first and second stages (W₁/W₂) with perfect intercooling is given by

A. W₁/W₂ = n₂(n₁ - 1)/n₁(n₂ - 1)

B. W₁/W₂ = n₁(n₂ - 1)/n₂(n₁ - 1)

C. W₁/W₂ = n₁/n₂

D. W₁/W₂ = n₂/n₁

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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

A compressor at high altitude will draw

A. More power

B. Less power

C. Same power

D. More/less power depending on other factors

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4

Diffuser in a compressor is used to

A. Increase velocity

B. Make the flow streamline

C. Convert pressure energy into kinetic energy

D. Convert kinetic energy into pressure energy

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4

The ratio of the indicated power to the shaft power or brake power of the motor or engine required to drive the compressor, is called

A. Compressor efficiency

B. Volumetric efficiency

C. Isothermal efficiency

D. Mechanical efficiency

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4

Reheating in a gas turbine

A. Increases the thermal efficiency

B. Increases the compressor work

C. Increases the turbine work

D. Decreases the thermal efficiency

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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

Which of the following statement is wrong?

A. In a two stage reciprocating air compressor with complete intercooling, maximum work is saved.

B. The minimum work required for a two stage reciprocating air compressor is double the work required for each stage.

C. The ratio of the volume of free air delivery per stroke to the swept volume of the piston is called volumetric efficiency.

D. None of the above

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4

A closed gas turbine in which fuel is burnt directly in the air is not possible because of

A. Paucity of O2

B. Increasing gas temperature

C. High specific volume

D. High friction losses

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4

In multistage compressor, the isothermal compression is achieved by

A. Employing intercooler

B. By constantly cooling the cylinder

C. By running compressor at very slow speed

D. By insulating the cylinder

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4

In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during

A. Isothermal compression

B. Isentropic compression

C. Polytropic compression

D. None of these