IES Mechanical Engineering Paper Set for practice

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Compressor ,Gas Turbine and Jet engine Paper set 3

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Efficiency of gas turbine is increased by

1 reheating

2 inter cooling

3 adding a regenerator

4 all of the above

The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio

1 increases

2 decreases

3 first increases and then decreases

4 first decreases and then increases

The ideal efficiency of simple gas turbine cycle depends on

1 pressure ratio

2 maximum cycle temperature

3 minimum cycle temperature

4 all of the above

Gas turbines use following type of air compressor

1 centrifugal type

2 reciprocating type

3 lobe type

4 axial flow type

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

1 increases

2 decreases

3 remains same

4 first increases and then decreases

5 first decreases and then increases.

The material commonly used for air craft gas turbine is

1 stainless steel

2 high alloy’ steel

3 duralumin

4 Timken, Haste and Inconel allpys

5 titanium

he combustion efficiency of a gas turbine using perfect combustion chamber is of the order of

1 50%

2 75%

3 85%

4 90%

5 99%

Producer gas is produced by

1 carbonisation of coal

2 passing steam over incandescent coke

3 passing air and a large amount of steam over waste coal at about 65°C

4 partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

For an irreversible gas turbine cycle, the efficiency and work ratio both depend on

1 pressure ratio alone

2 maximum cycle temperature alone

3 minimum cycle temperature alone

4 both pressure ratio and maximum cycle temperature

Water gas is produced by

1 carbonisation of coal

2 passing steam over incandescent coke

3 passing air and a large amount of steam over waste coal at about 65°C

4 partial combustion of caol, eke, anthractie coal or charcoal in a mixed air steam blast

Water is injected in gas turbine cycle to

1 control temperature

2 control output of turbine

3 control fire hazards

4 increase efficiency

The closed cycle in gas turbines

1 provides greater flexibility

2 provides lesser flexibility

3 in never used

4 is used when gas is to be burnt

After-cooler is used to

1 decrease the delivery temperature for ease in handling

2 cause moisture and oil vapour to drop out

3 reduce volume

4 increase pressure.

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

1 lowest

2 highest

3 anything

4 atmospheric

Rotary compressor is best suited for

1 large quantity of air at high pressure

2 small quantity of air at high pressure

3 small quantity of air at low pressure

4 large quantity of air at low pressure

Reciprocating air compressor is best suited for

1 large quantity of air at high pressure

2 small quantity of air at high pressure

3 small quantity of air at low pressure

4 large quantity of air at low pressure

In multistage compressor, the isothermal compression is achieved by

1 employing intercooler

2 by constantly cooling the cylinder

3 by running compressor at very slow speed

4 by insulating the cylinder

Which is false statement about multistage compression

1 Power consumption per unit of air delivered is low

2 Volumetric efficiency is high

3 It is best suited for compression ratios around 7:1

4 The moisture in air is condensed in the intercooler

5 Outlet temperature is reduced

Mining industry usually employs following motive power

1 A.C. electric motor

2 compressed air

3 petrol engine

4 diesel engine

5 D.C. electric motor

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

1 from an air conditioned room maintained at 20°C

2 from outside atmosphere at 1°C

3 from coal yard side

4 from a side where cooling tower is located nearby

5 from any one of the above locations

Euler’s equation is applicable for

1 centrifugal compressor

2 axial compressor

3 pumps

4 all of the above