In a turbo jet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in
Exit nozzle, which is a constant volume process
Exit nozzle, which is essentially an isentropic process
Turbine blades, which is a constant volume process
Turbine blades, which is essentially an isentropic process
Correct Answer :
D. Turbine blades, which is essentially an isentropic process
Related Questions
The air is delivered ________ in one revolution in case of a three lobbed rotor.
Two times
Three times
Four times
Six times
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
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
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
In air breathing jet engine, the jet is formed by expanding
Highly heated atmospheric air
Solids
Liquid
Plasma
The main purpose of reheating in gas turbine is to
Increase temperature
Reduce turbine size
Increase power output
Increase speed
A closed cycle gas turbine consists of a
Compressor
Heating chamber
Cooling chamber
All of these
In a double acting compressor, the air is compressed
In one cylinder
In two cylinders
In a single cylinder on both sides of the piston
In two cylinders on both sides of the piston
In multistage compressor, the isothermal compression is achieved by
Employing intercooler
By constantly cooling the cylinder
By running compressor at very slow speed
By insulating the cylinder
For perfect intercooling in a two stage compressor
p₂/p₁ = p₃/p₂
p₁/p₃ = p₂/p₁
p₁ = p₃
p₁ = p₂ p₃
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
Mining industry usually employs following motive power
A.C. electric motor
Compressed air
Petrol engine
Diesel engine
A gas turbine used in air craft should have
High h.p. and low weight
Low weight and small frontal area
Small frontal area and high h.p.
High speed and high h.p
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
Gas turbine blades are given a rake
Equal to zero
In the direction of motion of blades
Opposite to the direction of motion of blades
Depending on the velocity
A compressor at high altitude will draw
More power
Less power
Same power
More/less power depending on other factors
In a closed cycle gas turbine, the air is compressed
Isothermally
Polytropically
Isentropically
None of these
Which is false statement about advantages of multistage compressor in comparison to single stage compressor?
Less power requirement
Better mechanical balance
Less loss of air due to leakage past the cylinder
Lower volumetric efficiency
The pressure ratio of an ideal vaned compressor with increase in mass flow rate
Increases
Decreases
Remain constant
First decreases and then increases
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
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
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
The thermodynamic efficiency of rotary compressor is based on
Isothermal compression
Adiabatic compression
Isentropic compression
Polytropic compression
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
Reheating in multistage expansion gas turbine results in
High thermal efficiency
Reduction in compressor work
Decrease of heat loss in exhaust
Maximum work output
The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is
Heated
Compressed air before entering the combustion chamber is heated
Bled gas from turbine is heated and readmitted for complete expansion
Exhaust gases drive the compressor
Which of the following fuels can be used in turbojet engines?
Liquid hydrogen
High speed diesel oil
Kerosene
Methyl alcohol
When air is to be compressed at a high pressure, then it is advantageous to use
Single stage compression
Multistage compression without intercooling
Multistage compression with intercooling
None of these
The mass of gas turbine per kW developed is about ________ as that of an I.C. engine.
Same
One-half
One fourth
One sixth
Reheating in a multistage expansion gas turbine __________ compressor work.
Has no effect on
Decreases
Increases
None of these