Phenomenon of choking in compressor means
No flow of air
Fixed mass flow rate regardless of pressure ratio
Reducing mass flow rate with increase in pressure ratio
Increased inclination of chord with air steam
Correct Answer :
B. Fixed mass flow rate regardless of pressure ratio
Related Questions
The pressure of air at the beginning of the compression stroke is ________ the atmospheric pressure.
Equal to
Less than
More than
None of these
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
In a jet propulsion
The propulsive matter is ejected from within the propelled body
The propulsive matter is caused to flow around the propelled body
Its functioning does not depend upon presence of air
None of the above
The mass of gas turbine per kW developed is about ________ as that of an I.C. engine.
Same
One-half
One fourth
One sixth
In axial flow compressor, exit flow angle deviation from the blade angle is a function of
Blade camber
Blade camber and incidence angle
Spacechord ratio
Blade camber and spacechord ratio
For speed above 3000 km/hour, it is more advantageous to use
Turbojet engine
Ramjet engine
Propellers
Rockets
A rocket engine for the combustion of its fuel
Carries its own oxygen
Uses surrounding air
Uses compressed atmospheric air
Does not require oxygen
Ramjet engine
Is self operating at zero flight speed
Is not self operating at zero flight speed
Requires no air for its operation
Produces a jet consisting of plasma
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 efficiency of roots blower ________ with the increase in pressure ratio.
Decreases
Increases
Does not change
None of these
For supplying intermittent small quantity of air at high pressure, following compressor is best suited
Centrifugal
Reciprocating
Axial
Screw
The working fluid in a turbine is
In two phases
In three phases
In a single phase
In the form of air and water mixture
Which is false statement about multistage compression?
Power consumption per unit of air delivered is low
Volumetric efficiency is high
It is best suited for compression ratios around 7:1
The moisture in air is condensed in the intercooler
The maximum temperature in a gas turbine is
200°C
500°C
700°C
1000°C
High air-fuel ratio is used in gas turbines
To increase the output
To increase the efficiency
To save fuel
To reduce the exit temperature
The effective power of gas turbines is increased by adding the following in compressor
Ammonia and water vapour
Carbon dioxide
Nitrogen
Hydrogen
Volumetric efficiency of a compressor without clearance volume
Increases with increase in compression ratio
Decreases with increase in compression ratio
Is not dependent upon compression ratio
May increase/decrease depending on compressor capacity
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
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 volumetric efficiency of compressor with increase in compression ratio will
Increase
Decrease
Remain same
May increase or decrease depending on clearance volume
In turbo fan engine, the jet velocity as compared to turbojet engine is
Less
More
Same
May be less or more depending upon speed
Air-fuel ratio in a jet engine will be of the order of
10 : 1
15 : 1
20 : 1
60 : 1
A closed gas turbine in which fuel is burnt directly in the air is not possible because of
Paucity of O2
Increasing gas temperature
High specific volume
High friction losses
In a four stage compressor, if the pressure at the first and third stage is 1 bar and 16 bar, then the delivery pressure at the fourth stage will be
1 bar
16 bar
64 bar
256 bar
Rotary compressors are used for delivering
Small quantities of air at high pressures
Large quantities of air at high pressures
Small quantities of air at low pressures
Large quantities of air at low pressures
Which of the following statement is wrong?
In a two stage reciprocating air compressor with complete intercooling, maximum work is saved.
The minimum work required for a two stage reciprocating air compressor is double the work required for each stage.
The ratio of the volume of free air delivery per stroke to the swept volume of the piston is called volumetric efficiency.
None of the above
Inter-cooling in multistage compressors is done
To cool the air during compression
To cool the air at delivery
To enable compression in two stages
To minimise the work of compression
Efficiency of gas turbine is increased by
Reheating
Inter cooling
Adding a regenerator
All of the above
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
Propulsive efficiency is defined as ratio of
Thrust power and fuel energy
Engine output and propulsive power
Propulsive power and fuel input
Thrust power and propulsive power