For an irreversible gas turbine cycle, the efficiency and work ratio both depend on
Pressure ratio alone
Maximum cycle temperature alone
Minimum cycle temperature alone
Both pressure ratio and maximum cycle temperature
Correct Answer :
D. Both pressure ratio and maximum cycle temperature
Related Questions
In which case the air-fuel ratio is likely to be maximum?
Gas turbine
4-stroke petrol engine
4-stroke diesel engine
Multi cylinder engine
Which of the following statement is correct relating to rocket engines?
The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel
The stagnation conditions exist at the combustion chamber
The exit velocities of exhaust gases are much higher than those in jet engine
All of the above
The velocity of air entering in a rocket is ________ as compared to an aircraft.
Zero
Less
More
Same
The ratio of isentropic work to Euler work is known as
Pressure coefficient
Work coefficient
Polytropic reaction
Slip factor
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 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
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
Volumetric efficiency of air compressors is of the order of
20 - 30 %
40 - 50 %
60 - 70 %
70 - 90 %
For speed above 3000 km/hour, it is more advantageous to use
Turbojet engine
Ramjet engine
Propellers
Rockets
For maximum work, the reheating should be done to an intermediate pressure of (Where p₁ = Maximum pressure, and p₂ = Minimum pressure)
(p₁ - p₂)/2
(p₁ + p₂)/2
p₁/p₂
p₁ p₂
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
Volumetric efficiency of a compressor with clearance volume
Increases with increase in compression ratio
Decreases with increase in compression ratio
In not dependent upon compression ratio
May increase/decrease depending on compressor capacity
Which one of the following is the effect of blade shape on performance of a centrifugal compressor?
Backward curved blades has poor efficiency
Backward curved blades lead to stable performance
Forward curved blades has higher efficiency
Forward curved blades produce lower pressure ratio
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
In a centrifugal compressor, an increase in speed at a given pressure ratio causes
Increase in flow
Decrease in flow
Increase in efficiency
Increase in flow and decrease in efficiency
Fighter bombers use following type of engine
Turbojet
Turbo-propeller
Rocket
Ramjet
The pressure ratio in gas turbines is of the order of
2 : 1
4 :1
61 : 1
9 : 1
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
In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into
Atmosphere
Vacuum
Discharge nozzle
Back to the compressor
The compression ratio for the compressor is always __________ unity.
Equal to
Less than
More than
None of these
Inter-cooling in gas turbine results in
Increase in net output but decrease in thermal efficiency
Increase in thermal efficiency but decrease in net output
Increase in both thermal efficiency and net output
Decrease in both thermal efficiency and net output
Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on
Mass flow rate
Pressure ratio
Change in load
Stagnation pressure at the outlet
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
Losses in a centrifugal compressor are due to
Inlet losses
Impeller channel losses
Diffuser losses
All of the above
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
A large clearance volume in a reciprocating compressor results in
Reduced volume flow rate
Increased volume flow rate
Lower suction pressure
Lower delivery pressure
The absolute pressure of air at the outlet of a compressor is called
Back pressure
Critical pressure
Discharge pressure
None of these
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
The inlet pressure is always ________ the discharge pressure.
Equal to
Less than
More than
None of these