Maximum temperature in a gas turbine is of the order of
700°C
2000°C
1500°C
1000°C
Correct Answer :
A. 700°C
Related Questions
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
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
The ratio of the discharge pressure to the inlet pressure of air is called
Compression ratio
Expansion ratio
Compressor efficiency
Volumetric efficiency
In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of workdone on the first and second stages (W₁/W₂) with perfect intercooling is given by
W₁/W₂ = n₂(n₁ - 1)/n₁(n₂ - 1)
W₁/W₂ = n₁(n₂ - 1)/n₂(n₁ - 1)
W₁/W₂ = n₁/n₂
W₁/W₂ = n₂/n₁
Which of the following fuels can be used in turbojet engines?
Liquid hydrogen
High speed diesel oil
Kerosene
Methyl alcohol
In a single acting reciprocating air compressor, without clearance, the compression of air may be
Isothermal
Polytropic
Isentropic
Any one of these
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 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
The compressor capacity with decrease in suction temperature
Increases
Decreases
Remain unaffected
May increase or decrease depending on compressor capacity
In a centrifugal compressor, the flow of air is ________ to the axis of compressor.
Parallel
Perpendicular
Inclined
None of these
Air-fuel ratio in a jet engine will be of the order of
10 : 1
15 : 1
20 : 1
60 : 1
The maximum compression ratio in an actual single stage axial flow compressor is of the order of
1 : 1.2
1 : 2
1 : 5
1 : 10
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
The inlet pressure is always ________ the discharge pressure.
Equal to
Less than
More than
None of these
The absolute pressure of air at the outlet of a compressor is called
Back pressure
Critical pressure
Discharge pressure
None 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
The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called
Slip factor
Velocity factor
Velocity coefficient
None of the above
The performance of air compressor at high altitudes will be ________ as compared to that at sea level.
Same
Lower
Higher
None of these
Reheating in a gas turbine
Increases the thermal efficiency
Increases the compressor work
Increases the turbine work
Decreases the thermal efficiency
Separators are generally used in air compressor installations
Before the intercooler
After the intercooler
Between the aftercooler and receiver
Before first stage suction
In gas turbines, high thermal efficiency is obtained in
Closed cycle
Open cycle
Both of the above
Closed/open depending on other considerations
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
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
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
In the aircraft propellers
The propulsive matter is caused to flow around the propelled body
Propulsive matter is ejected from within the propelled body
Its functioning does not depend on presence of air
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
Open cycle gas turbine works on
Brayton or Atkinson cycle
Rankine cycle
Carnot cycle
Erricson cycle
Adiabatic compression is one in which
Temperature during compression remains constant
No heat leaves or enters the compressor cylinder during compression
Temperature rise follows a linear relationship
Work done is maximum
Standard air is the air at
Atmospheric conditions at any specific location
20°C and 1 kg/cm² and relative humidity 36%
0°C and standard atmospheric conditions
15°C and 1 kg/cm²
The air-fuel ratio in gas turbines is of the order of
7 : 1
15 : 1
30 : 1
50 : 1.