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4

The pressure ratio of an ideal vaned compressor with increase in mass flow rate

A. Increases

B. Decreases

C. Remain constant

D. First decreases and then increases

Correct Answer :

C. Remain constant


Related Questions

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4

The volumetric efficiency for reciprocating air compressors is about

A. 10 to 40 %

B. 40 to 60 %

C. 60 to 70 %

D. 70 to 90 %

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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

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

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

The compressor efficiency is the

A. Isothermal H.P/indicated H.R

B. Isothermal H.P./shaft H.R

C. Total output/air input

D. Compression work/motor input

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4

The closed cycle in gas turbines

A. Provides greater flexibility

B. Provides lesser flexibility

C. In never used

D. Is used when gas is to be burnt

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4

A jet engine works on the principle of conservation of

A. Mass

B. Energy

C. Flow

D. Linear momentum

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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

Open cycle gas turbine works on

A. Brayton or Atkinson cycle

B. Rankine cycle

C. Carnot cycle

D. Erricson cycle

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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

Volumetric efficiency is

A. The ratio of stroke volume to clearance volume

B. The ratio of the air actually delivered to the amount of piston displacement

C. Reciprocal of compression ratio

D. Index of compressor performance

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4

Out of the following, from where you will prefer to take intake for air compressor

A. From an air conditioned room maintained at 20°C

B. From outside atmosphere at 1°C

C. From coal yard side

D. From a side where cooling tower is located nearby

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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

In open cycle turbojet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the

A. Thrust and range of aircraft

B. Efficiency of the engine

C. Both (A) and (B)

D. None of these

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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 compressor at high altitudes will require ________ power.

A. Same

B. Less

C. More

D. None of these

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4

The efficiency of jet engine is

A. Lower at low speed

B. Higher at high altitudes

C. Same at all altitudes

D. Higher at high speed

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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

To avoid moisture troubles, the branch connections from compressed air lines should be taken from

A. Top side of main

B. Bottom side of main

C. Left side of main

D. Right side of main

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4

The most efficient method of compressing air is to compress it

A. Isothermally

B. Adiabatically

C. Isentropically

D. Isochronically

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4

Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is

A. Higher

B. Lower

C. Equal

D. Cant be compared

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4

High air-fuel ratio in gas turbines

A. Increases power output

B. Improves thermal efficiency

C. Reduces exhaust temperature

D. Do not damage turbine blades

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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

Reheating in gas turbine results in

A. Increase of work ratio

B. Decrease of thermal efficiency

C. Decrease of work ratio

D. Both (A) and (B) above

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4

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 pressure ratio in gas turbines is of the order of

A. 2 : 1

B. 4 :1

C. 61 : 1

D. 9 : 1

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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 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

Efficiency of gas turbine is increased by

A. Reheating

B. Inter cooling

C. Adding a regenerator

D. All of the above

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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