Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is
Higher
Lower
Equal
Cant be compared
Correct Answer :
B. Lower
Related Questions
Volumetric efficiency of air compressors is of the order of
20 - 30 %
40 - 50 %
60 - 70 %
70 - 90 %
It is not possible to use closed gas turbine cycle in aeronautical engines because
It is inefficient
It is bulky
It requires cooling water for its operation
None of the above
The maximum combustion pressure in gas turbine as compared to I.C. engine is
More
Less
Same
Depends on other factors
The maximum delivery pressure in a rotary air compressor is
10 bar
20 bar
30 bar
50 bar
Pick up the wrong statement about advantages of multistage compression
Better lubrication is possible advantages of multistage
More loss of air due to leakage past the cylinder
Mechanical balance is better
Air can be cooled perfectly in between
The absolute pressure of air at the outlet of a compressor is called
Back pressure
Critical pressure
Discharge pressure
None of these
A rotary compressor is driven by an
Electric motor
Engine
Either (A) or (B)
None of these
The output of a gas turbine is 300 KW and its efficiency is 20 percent, the heat supplied is
6000 KW
15 KW
600 KW
150 KW
Ram compression in turbojet involves
Reduction of speed of incoming air and conversion of part of it into pressure energy
Compression of inlet air
Increasing speed of incoming air
Lost work
Which of the following statement is correct?
The reciprocating compressors are best suited for high pressure and low volume capacity
The effect of clearance volume on power consumption is negligible for the same volume of discharge
Both (A) and (B)
None of these
The ratio of specific weight/h.p. of gas turbine and I.C engines may be typically of the order of
1 : 1
2 : 1
4 : 1
1 : 6
For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is pa, then the intermediate pressure p₂ is given by
p₂ = (p₁ + p₃)/2
p₂ = p₁. p₃
P₂ = Pa × p₃/p₁
p₂ = Pa p₃/p₁
The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the
Adiabatic temperature drop in the stage
Total temperature drop
Total temperature drop in the stage
Total adiabatic temperature drop
The mean effective pressure of the compressor is the
Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions
Volume of air delivered by the compressor
Volume of air sucked by the compressor during its suction stroke
None of the above
The volume of air sucked by the compressor during its suction stroke is called
Free air delivery
Compressor capacity
Swept volume
None of these
The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called
Slip factor
Velocity factor
Velocity coefficient
None of the above
Maximum work is done in compressing air when the compression is
Isothermal
Adiabatic
Polytropic
None of the above
Work ratio of a gas turbine may be improved by
Decreasing the compression work
Increasing the compression work
Increasing the turbine work
Both (A) and (C) above
The clearance volume of the air compressor is kept minimum because
It allows maximum compression to be achieved
It greatly affects volumetric efficiency
It results in minimum work
It permits isothermal compression
For perfect intercooling in a two stage compressor
p₂/p₁ = p₃/p₂
p₁/p₃ = p₂/p₁
p₁ = p₃
p₁ = p₂ p₃
Volumetric efficiency of a compressor decreases with ________ in compression ratio.
Decrease
Increase
Remain same
Does not change
The efficiency of a jet engine is higher at
Low speeds
High speeds
Low altitudes
High altitudes
The material commonly used for air craft gas turbine is
Stainless steel
High alloy steel
Duralumin
Timken, Haste alloys
A machine used to raise the pressure of air is called
Gas turbine
I.C engine
Compressor
Air motor
The pressure and temperature conditions of air at the suction of compressor are
Atmospheric
Slightly more than atmospheric
Slightly less than atmospheric
Pressure slightly less than atmospheric and temperature slightly more than atmospheric
The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
Pressure drop across the valves
Superheating in compressor
Clearance volume and leakages
All of these
Which of the following statement is correct as regard to centrifugal compressors?
The flow of air is parallel to the axis of the compressor
The static pressure of air in the impeller increases in order to provide centripetal force on the air
The impeller rotates at high speeds
The maximum efficiency is higher than multistage axial flow compressors
Stalling of blades in axial flow compressor is the phenomenon of
Air stream blocking the passage
Motion of air at sonic velocity
Unsteady periodic and reversed flow
Air stream not able to follow the blade contour
A rocket engine for the combustion of its fuel
Carries its own oxygen
Uses surrounding air
Uses compressed atmospheric air
Does not require oxygen
Gas turbine blades are given a rake
Equal to zero
In the direction of motion of blades
Opposite to the direction of motion of blades
Depending on the velocity