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4

Clearance volume in actual reciprocating compressors is essential

A. To accommodate Valves in the cylinder head

B. To provide cushioning effect

C. To attain high volumetric efficiency

D. To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head

Correct Answer :

D. To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head


Related Questions

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The maximum compression ratio in an actual single stage axial flow compressor is of the order of

A. 1 : 1.2

B. 1 : 2

C. 1 : 5

D. 1 : 10

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4

The capacity of compressor will be highest when its intake temperature is

A. Lowest

B. Highest

C. Anything

D. Atmospheric

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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

A 3 m³/min compressor means that it

A. Compresses 3 m³/min of standard air

B. Compresses 3 m³/ min of free air

C. Delivers 3 m³/ min of compressed air

D. Delivers 3 m³/ min of compressed air at delivery pressure

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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 ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called

A. Slip factor

B. Velocity factor

C. Velocity coefficient

D. None of the above

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4

The efficiency of a jet engine is higher at

A. Low speeds

B. High speeds

C. Low altitudes

D. High altitudes

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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

Volumetric efficiency of a compressor decreases with ________ in compression ratio.

A. Decrease

B. Increase

C. Remain same

D. Does not change

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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

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

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

In a centrifugal compressor, the flow of air is ________ to the axis of compressor.

A. Parallel

B. Perpendicular

C. Inclined

D. None of these

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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

Maximum temperature in a gas turbine is of the order of

A. 700°C

B. 2000°C

C. 1500°C

D. 1000°C

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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

Fighter bombers use following type of engine

A. Turbojet

B. Turbo-propeller

C. Rocket

D. Ramjet

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4

Intercooling in gas turbines

A. Decreases net output but increases thermal efficiency

B. Increases net output but decreases thermal efficiency

C. Decreases net output and thermal efficiency both

D. Increases net output and thermal efficiency both

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4

The blades of gas turbine are made of

A. High nickel alloy

B. Stainless steel

C. Carbon steel

D. High alloy steel

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4

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

A. Isothermal h.p. to the BHP of motor

B. Isothermal h.p. to adiabatic h.p.

C. Power to drive compressor to isothermal h.p.

D. Work to compress air isothermally to work for actual compression

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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

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

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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

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 compression ratio in a gas turbine is of the order of

A. 3.5 : 1

B. 5 : 1

C. 8 : 1

D. 12 : 1

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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

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

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

Phenomenon of choking in compressor means

A. No flow of air

B. Fixed mass flow rate regardless of pressure ratio

C. Reducing mass flow rate with increase in pressure ratio

D. Increased inclination of chord with air steam

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4

More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than

A. 2 kg/cm²

B. 6 kg/cm²

C. 10 kg/cm²

D. 14.7 kg/cm²