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Compressors, Gas Turbines and Jet Engines MCQ Practice Test - Set 01
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Compressors, Gas Turbines and Jet Engines MCQ Practice Test - Set 01
1
If the flow of air through the compressor is perpendicular to its axis, then it is a
A
Reciprocating compressor
B
Centrifugal compressor
C
Axial flow compressor
D
Turbo compressor
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✅ Correct Answer: 2
2
Gas turbines use following type of air compressor
A
Centrifugal type
B
Reciprocating type
C
Lobe type
D
Axial flow type
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✅ Correct Answer: 4
3
The gas in cooling chamber of a closed cycle gas turbine is cooled at
A
Constant volume
B
Constant temperature
C
Constant pressure
D
None of these
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✅ Correct Answer: 3
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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✅ Correct Answer: 2
5
In a closed cycle gas turbine, the air is compressed
A
Isothermally
B
Polytropically
C
Isentropically
D
None of these
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✅ Correct Answer: 3
6
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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✅ Correct Answer: 1
7
The closed cycle in gas turbines
A
Provides lesser flexibility
B
Provides lesser flexibility
C
In never used
D
Is used when gas is to be burnt
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✅ Correct Answer: 1
8
The overall thermal efficiency of an ideal gas turbine plant is (where r = Pressure ratio)
A
r ɣ-1
B
1 - r ɣ-1
C
1 - (1/r) ɣ-1/ɣ
D
1 - (1/r) ɣ/ɣ-1
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✅ Correct Answer: 3
9
Pick up the correct statement
A
Large gas turbines use radial inflow turbines
B
Gas turbines have their blades similar to steam turbine
C
Gas turbine's blade will appear as impulse section at the hub and as a reaction section at tip
D
Gas turbines use both air and liquid cooling
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✅ Correct Answer: 3
10
The degree of reaction is usually kept ________ for all types of axial flow compressors.
A
0.2
B
0.3
C
0.4
D
0.5
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✅ Correct Answer: 4
11
Ram compression in turbojet involves
A
Reduction of speed of incoming air and conversion of part of it into pressure energy
B
Compression of inlet air
C
Increasing speed of incoming air
D
Lost work
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✅ Correct Answer: 1
12
A compressor mostly used for supercharging of I.C. engines is
A
Radial flow compressor
B
Axial flow compressor
C
Roots blower
D
Reciprocating compressor
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✅ Correct Answer: 1
13
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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✅ Correct Answer: 3
14
The work-done on a compressor will be minimum if air is taken from
A
The atmosphere
B
A source at 0° C
C
A source of low temperature air
D
A source of high temperature air
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✅ Correct Answer: 3
15
In the aircraft propellers
A
The propulsive matter is caused to flow around the propelled body
B
Propulsive matter is ejected from within the propelled body
C
Its functioning does not depend on presence of air
D
All of the above
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✅ Correct Answer: 4
16
In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into
A
Atmosphere
B
Vacuum
C
Discharge nozzle
D
Back to the compressor
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✅ Correct Answer: 3
17
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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✅ Correct Answer: 1
18
In an axial flow compressor, the ratio of pressure in the rotor blades to the pressure rise in the compressor in one stage is known as
A
Work factor
B
Slip factor
C
Degree of reaction
D
Pressure coefficient
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✅ Correct Answer: 3
19
To avoid moisture troubles, the compressed air main line should
A
Rise gradually towards the point of use
B
Drop gradually towards the point of use
C
Be laid vertically
D
Be laid exactly horizontally
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✅ Correct Answer: 2
20
The volumetric efficiency of a compressor
A
Increases with decrease in compression ratio
B
Decreases with decrease in compression ratio
C
Increases with increase in compression ratio
D
Decreases with increase in compression ratio
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✅ Correct Answer: 4
21
The efficiency and work ratio of a gas turbine plant can be increased by
A
Adding heat exchanger
B
Injecting water in/around combustion chamber
C
Reheating the air after partial expansion in the turbine
D
All of the above
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✅ Correct Answer: 4
22
The capacity of compressor will be highest when its intake temperature is
A
Lowest
B
Highest
C
Anything
D
Atmospheric
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✅ Correct Answer: 4
23
The volume of air sucked by the compressor during its suction stroke is called
A
Free air delivery
B
Compressor capacity
C
Swept volume
D
None of these
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✅ Correct Answer: 3
24
Which is false statement about multistage compression?
A
Power consumption per unit of air delivered is low
B
Volumetric efficiency is high
C
It is best suited for compression ratios around 7:1
D
The moisture in air is condensed in the inter-cooler
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✅ Correct Answer: 2
25
Standard air is the air at ________ and relative humidity of 36 percent.
A
0.1 bar and 20°C
B
1 bar and 20°C
C
0.1 bar and 40°C
D
1 bar and 40°C
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✅ Correct Answer: 2
26
Out of the following, from where you will prefer to take intake for air compressor
A
0.1 bar and 20°C
B
1 bar and 20°C
C
0.1 bar and 40°C
D
1 bar and 40°C
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✅ Correct Answer: 2
27
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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✅ Correct Answer: 4
28
When air is to be compressed at a high pressure, then it is advantageous to use
A
Single stage compression
B
Multistage compression without intercooling
C
Multistage compression with intercooling
D
None of these
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✅ Correct Answer: 3
29
In multistage compressor, the isothermal compression is achieved by
A
Employing inter-cooler
B
By constantly cooling the cylinder
C
By running compressor at very slow speed
D
By insulating the cylinder
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✅ Correct Answer: 3
30
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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✅ Correct Answer: 2
31
The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is
A
Less
B
More
C
Same
D
More/less depending on compressor capacity
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✅ Correct Answer: 2
32
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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✅ Correct Answer: 2
33
Separators in compressor installations are located
A
Before inter-cooler
B
After inter-cooler
C
After receiver
D
Between after-cooler and air receiver
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✅ Correct Answer: 4
34
Pick up the wrong statement
A
Pulse-jet 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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✅ Correct Answer: 1
35
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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✅ Correct Answer: 4
36
Reciprocating air compressor is best suited for
A
Large quantity of air at high pressure
B
Small quantity of air at high pressure
C
Small quantity of air at low pressure
D
Large quantity of air at low pressure
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✅ Correct Answer: 1
37
. Reciprocating air compressor is best suited for
A
Large quantity of air at high pressure
B
Small quantity of air at high pressure
C
Small quantity of air at low pressure
D
Large quantity of air at low pressure
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✅ Correct Answer: 1
38
In a double acting compressor, the air is compressed
A
In one cylinder
B
In two cylinders
C
In a single cylinder on both sides of the piston
D
In two cylinders on both sides of the piston
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✅ Correct Answer: 3
39
After-cooler is used to
A
Cool the air
B
Decrease the delivery temperature for ease in handling
C
Cause moisture and oil vapour to drop out
D
Reduce volume
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✅ Correct Answer: 3
40
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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✅ Correct Answer: 3
41
Mining industry usually employs following motive power
A
A.C. electric motor
B
Compressed air
C
Petrol engine
D
Diesel engine
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✅ Correct Answer: 2
42
The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
A
Pressure drop across the valves
B
Superheating in compressor
C
Clearance volume and leakages
D
All of the above
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✅ Correct Answer: 4
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