The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature
0.1 %
0.5 %
1 %
5 %
Correct Answer :
C. 1 %
Related Questions
The stagnation pressure rise in a centrifugal compressor takes place
In the diffuser only
In the impeller only
In the diffuser and impeller
In the inlet guide vanes only
For minimum work in multistage compression, assuming same index of compression in all stages
Work done in first stage should be more
Work done in subsequent stages should increase
Work done in subsequent stages should decrease
Work done in all stages should be equal
Rotary compressor is best suited for
Large quantity of air at high pressure
Small quantity of air at high pressure
Small quantity of air at low pressure
Large quantity of air at low pressure
Gas turbine works on
Brayton or Atkinson cycle
Carnot cycle
Rankine cycle
Erricson cycle
The overall thermal efficiency of an ideal gas turbine plant is (where r = Pressure ratio)
r -1
1 - r -1
1 - (1/r) -1/
1 - (1/r) /-1
The propulsive power of the rocket is (where v₁ = Jet velocity, and v₂ = Aircraft velocity)
(v₁² -v₂²)/2g
(v₁ - v₂)²/2g
(v₁² -v₂²)/g
(v₁ - v₂)²/g
In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of
Vacuum
Atmospheric air
Compressed air
Oxygen alone
Fighter bombers use following type of engine
Turbojet
Turbo-propeller
Rocket
Ramjet
The volume of air delivered by the compressor is called
Free air delivery
Compressor capacity
Swept volume
None of these
The ratio of isentropic work to Euler work is known as
Pressure coefficient
Work coefficient
Polytropic reaction
Slip factor
The air is delivered ________ in one revolution in case of a three lobbed rotor.
Two times
Three times
Four times
Six times
Actual compression curve is
Same as isothermal
Same as adiabatic
Better than isothermal and adiabatic
In between isothermal and adiabatic
An aftercooler is used to
Remove impurities from air
Reduce volume of air
Cause moisture and oil vapour to drop out
Cool the air
The maximum combustion pressure in gas turbine as compared to I.C. engine is
More
Less
Same
Depends on other factors
The main purpose of reheating in gas turbine is to
Increase temperature
Reduce turbine size
Increase power output
Increase speed
A compressor at high altitudes will require ________ power.
Same
Less
More
None of these
The overall efficiency of the compressed air system is the
Ratio of shaft output of the air motor to the shaft input to the compressor
Ratio of shaft input to the compressor to the shaft output of air motor
Product of shaft output of air motor and shaft input to the compressor
None of the above
In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at
Diffuser inlet radius
Diffuser outlet radius
Impeller inlet radius
Impeller outlet radius
The fuel consumption in gas turbines is accounted for by
Lower heating value
Higher heating value
Heating value
Higher calorific value
Which of the following plants is smallest and lightest for generating a given amount of power?
Gas turbine plant
Petrol engine
Diesel engine
Solar plant
Intercooling in gas turbines
Decreases net output but increases thermal efficiency
Increases net output but decreases thermal efficiency
Decreases net output and thermal efficiency both
Increases net output and thermal efficiency both
The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio
Increases
Decreases
First increases and then decreases
First decreases and then increases
In a single stage, single acting reciprocating air compressor without clearance volume, the workdone is maximum during
Isothermal compression
Isentropic compression
Polytropic compression
None of these
After-cooler is used to
Cool the air
Decrease the delivery temperature for ease in handling
Cause moisture and oil vapour to drop out
Reduce volume
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
Thrust and range of aircraft
Efficiency of the engine
Both (A) and (B)
None of these
The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of
75 %
85 %
90 %
99 %
Pick up the wrong statement
Large gas turbines employ axial flow compressors
Axial flow compressors are more stable than centrifugal type compressors but not as efficient
Axial flow compressors have high capacity and efficiency
Axial flow compressors have instability region of operation
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
The pressure ratio in gas turbines is of the order of
2 : 1
4 :1
61 : 1
9 : 1
The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.
Equal to
Less than
More than
None of these