In jet propulsion power unit, the inlet duct of diverging shape is used in order to
Collect more air
Convert kinetic energy of air into pressure energy
Provide robust structure
Beautify the shape
Correct Answer :
B. Convert kinetic energy of air into pressure energy
Related Questions
The ratio of work done per cycle to the swept volume in case of compressor is called
Compression index
Compression ratio
Compressor efficiency
Mean effective pressure
The ratio of workdone per cycle to the stroke volume of the compressor is known as
Compressor capacity
Compression ratio
Compressor efficiency
Mean effective pressure
The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as
Compressor efficiency
Volumetric efficiency
Isothermal efficiency
Mechanical efficiency
During base load operation, the best method of controlling compressor is
Start-stop motor
Constant speed unloader
Relief valve
Variable speed
Maximum delivery pressure is a rotary air compressor is of the order of
6 kg/cm²
10 kg/cm²
16 kg/cm²
25 kg/cm²
A compressor mostly used for supercharging of I.C. engines is
Radial flow compressor
Axial flow compressor
Roots blower
Reciprocating compressor
The blades of gas turbine are made of
High nickel alloy
Stainless steel
Carbon steel
High alloy steel
Aeroplanes employ following type of compressor
Radial flow
Axial flow
Centrifugal
None of the above
Gas turbine cycle with regenerator
Increases thermal efficiency
Allows high compression ratio
Decreases heat loss is exhaust
Allows operation at very high altitudes
Turbofan engine employs
One air stream
Two or more air streams
No air stream
Solid fuel firing
The work ratio of simple gas turbine cycle depends on
Pressure ratio
Maximum cycle temperature
Minimum cycle temperature
All of the above
If the flow of air through the compressor is perpendicular to its axis, then it is a
Reciprocating compressor
Centrifugal compressor
Axial flow compressor
Turbo compressor
Cylinder clearance in a compressor should be
As large as possible
As small as possible
About 50% of swept volume
About 100% of swept volume
Which of the following statement is correct?
The ratio of the discharge pressure to the inlet pressure of air is called compressor efficiency
The compression ratio for the compressor is always greater than unity
The compressor capacity is the ratio of workdone per cycle to the stroke volume
During isothermal compression of air, the workdone in a compressor is maximum
Maximum temperature in a gas turbine is of the order of
700°C
2000°C
1500°C
1000°C
The criterion of the thermodynamic efficiency for rotary compressor is
Isentropic compression
Isothermal compression
Polytropic compression
None of the above
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
Actual compression curve is
Same as isothermal
Same as adiabatic
Better than isothermal and adiabatic
In between isothermal and adiabatic
During peak load periods, the best method of controlling compressors is
Start-stop motor
Constant speed unloader
Relief valve
Variable speed
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
There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would
Remain same
Decrease
Increase
None of the above
Surging 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
To avoid moisture troubles, the compressed air main line should
Rise gradually towards the point of use
Drop gradually towards the point of use
Be laid vertically
Be laid exactly horizontally
An air compressor may be controlled by
Throttle control
Clearance control
Blow off control
Any one of the above
Axial flow compressor resembles
Centrifugal pump
Reciprocating pump
Turbine
Sliding vane compressor
Reheating in gas turbine results in
Increase of work ratio
Decrease of thermal efficiency
Decrease of work ratio
Both (A) and (B) above
The compressor capacity with decrease in suction temperature
Increases
Decreases
Remain unaffected
May increase or decrease depending on compressor capacity
For a two stage compressor, if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will
Increase
Decrease
Remain unaffected
Other factors control it
Euler's equation is applicable for
Centrifugal compressor
Axial compressor
Pumps
All of the above
More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than
2 kg/cm²
6 kg/cm²
10 kg/cm²
14.7 kg/cm²