The ratio of isentropic work to Eulers work is known as
Compressor efficiency
Isentropic efficiency
Euler's efficiency
Pressure coefficient
Correct Answer :
D. Pressure coefficient
Related Questions
Pick up the correct statement
Large gas turbines use radial inflow turbines
Gas turbines have their blades similar to steam turbine
Gas turbine's blade will appear as impulse section at the hub and as a reaction section at tip
Gas turbines use both air and liquid cooling
An ideal air compressor cycle with clearance on PV diagram can be represented by following processes
One adiabatic, two isobaric, and one constant volume
Two adiabatic and two isobaric
Two adiabatic, one isobaric and one constant volume
One adiabatic, one isobaric and two constant volumes
In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of
Vacuum
Atmospheric air
Compressed air
Oxygen alone
The overall isothermal efficiency of the compressor is defined as the ratio of
Work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio
Isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor
Volume of free air delivery per stroke to the swept volume of the piston
Isentropic power to the power required to drive the compressor
Pick up the correct statement
Gas turbine uses low air-fuel ratio to economise on fuel
Gas turbine uses high air-fuel ratio to reduce outgoing temperature
Gas turbine uses low air-fuel ratio to develop the high thrust required
All of the above
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
When the temperature of air leaving the intercooler, in a two stage compression with intercooler, is ________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling.
Equal to
Less than
More than
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
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
The maximum propulsion efficiency of a turbojet is attained at around following speed
550 km/hr
1050 km/hr
1700 km/hr
2400 km/hr
The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation
0.1 %
0.5 %
1.0 %
5 %
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
The ratio of the discharge pressure to the inlet pressure of air is called
Compression ratio
Expansion ratio
Compressor efficiency
Volumetric efficiency
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
In jet engines, paraffin is usually used as the fuel because of its
High calorific value
Ease of atomisation
Low freezing point
Both (A) and (C) above
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
The following property is most important for material used for gas turbine blade
Toughness
Fatigue
Creep
Corrosion resistance
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 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
Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be
1.03 kg/cm²
1.06 kg/cm²
1.00 kg/cm²
0.53 kg/cm²
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
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 effective power of gas turbines is increased by adding the following in compressor
Ammonia and water vapour
Carbon dioxide
Nitrogen
Hydrogen
Actual compression curve is
Same as isothermal
Same as adiabatic
Better than isothermal and adiabatic
In between isothermal and adiabatic
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
Ram compression in turbojet involves
Reduction of speed of incoming air and conversion of part of it into pressure energy
Compression of inlet air
Increasing speed of incoming air
Lost work
Choose the correct statement
Gas turbine requires lot of cooling water
Gas turbine is capable of rapid start up and loading
Gas turbines has flat efficiency at part loads
Gas turbines have high standby losses and require lot of maintenance
The degree of reaction is usually kept ________ for all types of axial flow compressors.
0.2
0.3
0.4
0.5
A closed cycle gas turbine gives ________ efficiency as compared to an open cycle gas turbine.
Same
Lower
Higher
None of these
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