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
Correct Answer :
B. Axial flow compressors are more stable than centrifugal type compressors but not as efficient
Related Questions
Air-fuel ratio in a jet engine will be of the order of
10 : 1
15 : 1
20 : 1
60 : 1
The performance of air compressor at high altitudes will be ________ as compared to that at sea level.
Same
Lower
Higher
None of these
The air entry velocity m a rocket as compared to aircraft is
Same
More
Less
Zero
The net work input required for compressor with increase in clearance volume
Increases
Decreases
Remains same
Increases/decreases depending on compressor capacity
For perfect intercooling in a two stage compressor
p₂/p₁ = p₃/p₂
p₁/p₃ = p₂/p₁
p₁ = p₃
p₁ = p₂ p₃
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
Mining industry usually employs following motive power
A.C. electric motor
Compressed air
Petrol engine
Diesel engine
The compressor capacity is defined as 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
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
Aeroplanes employ following type of compressor
Radial flow
Axial flow
Centrifugal
None of the above
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
The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature
0.1 %
0.5 %
1 %
5 %
A closed cycle gas turbine works on
Carnot cycle
Rankine cycle
Ericsson cycle
Joule cycle
Water gas is produced by
Carbonisation of coal
Passing steam over incandescent coke
Passing air and a large amount of steam over waste coal at about 65°C
Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast
The assumption made in two stage compression with intercooler is that
There is no pressure drop in the intercooler
The compression in both the cylinders is polytropic
The suction and delivery of air takes place at constant pressure
All of the above
The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation
0.1 %
0.5 %
1.0 %
5 %
The work ratio of a gas turbine plant is defined as the ratio of
Net work output and heat supplied
Net work output and work done by turbine
Actual heat drop and isentropic heat drop
Net work output and isentropic heat drop
Rotary compressors are suitable for
Large discharge at high pressure
Low discharge at high pressure
Large discharge at low pressure
Low discharge at low pressure
Standard air is the air at ________ and relative humidity of 36 percent.
0.1 bar and 20°C
1 bar and 20°C
0.1 bar and 40°C
1 bar and 40°C
Work ratio of a gas turbine plant is ratio of
Net work output and work done by turbine
Net work output and heat supplied
Work done by turbine and heat supplied
Work done by turbine and net work output
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
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
Maximum work is done in compressing air when the compression is
Isothermal
Adiabatic
Polytropic
None of the above
For minimum work required to compress and deliver a quantity of air by multistage compression
The compression ratio in each stage should be same
The intercooling should be perfect
The workdone in each stage should be same
All of the above
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
When the outlet angle from the rotor of a centrifugal compressor is more than 90°, then the blades are said to be
Forward curved
Backward curved
Radial
None of these
Euler's equation can be used for
Radial flow compressors
Axial flow compressors
Pumps
All of these
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
In a single stage, single acting reciprocating air compressor, without clearance, the workdone on the air during isentropic compression is ________ the heat required to raise the temperature of air from T₁ to T₂ at a constant pressure.
Equal to
Less than
Greater than
None of these
Inter cooling in compressors
Cools the delivered air
Results in saving of power in compressing a given volume to given pressure
Is the standard practice for big compressors
Enables compression in two stages