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
Correct Answer :
B. Gas turbine is capable of rapid start up and loading
Related Questions
In air breathing jet engine, the jet is formed by expanding
Highly heated atmospheric air
Solids
Liquid
Plasma
Propulsive efficiency is defined as ratio of
Thrust power and fuel energy
Engine output and propulsive power
Propulsive power and fuel input
Thrust power and propulsive power
The pressure and temperature conditions of air at the suction of compressor are
Atmospheric
Slightly more than atmospheric
Slightly less than atmospheric
Pressure slightly less than atmospheric and temperature slightly more than atmospheric
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
A closed gas turbine in which fuel is burnt directly in the air is not possible because of
Paucity of O2
Increasing gas temperature
High specific volume
High friction losses
Reheating in gas turbine results in
Increase of work ratio
Decrease of thermal efficiency
Decrease of work ratio
Both (A) and (B) above
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
The overall efficiency of the compressed air system is the
Ratio of shaft output of the air motor to the shaft input to the compressor
Ratio of shaft input to the compressor to the shaft output of air motor
Product of shaft output of air motor and shaft input to the compressor
None of the above
The efficiency of a jet engine is higher at
Low speeds
High speeds
Low altitudes
High altitudes
The type of rotary compressor used in gas turbines, is of
Centrifugal type
Axial flow type
Radial flow type
None of these
Aeroplanes employ following type of compressor
Radial flow
Axial flow
Centrifugal
None of the above
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
In the axial flow gas turbine, the work ratio is the ratio of
Compressor work and turbine work
Output and input
Actual total head temperature drop to the isentropic total head drop from total head inlet to static head outlet
Actual compressor work and theoretical compressor work
In a jet engine, the air-fuel ratio is
30 : 1
40 : 1
50 : 1
60 : 1
The compressor capacity with decrease in suction temperature
Increases
Decreases
Remain unaffected
May increase or decrease depending on compressor capacity
Gas turbine works on
Brayton or Atkinson cycle
Carnot cycle
Rankine cycle
Erricson cycle
The compressed air may be used
In gas turbine plants
For operating pneumatic drills
In starting and supercharging of I.C. engines
All of the above
Water is injected in gas turbine cycle to
Control temperature
Control output of turbine
Control fire hazards
Increase efficiency
The compressor performance at higher altitude compared to sea level will be
Same
Higher
Lower
Dependent on other factors
Reheating in multistage expansion gas turbine results in
High thermal efficiency
Reduction in compressor work
Decrease of heat loss in exhaust
Maximum work output
What will be the volume of air at 327°C if its volume at 27°C is 1.5 m³/ mt?
3 m³/ mt.
1.5 m³/ mt.
18 m³/ mt.
6 m³/ mt.
The ratio of the net work obtained from the gas turbine plant to the turbine work is known as
Compression ratio
Work ratio
Pressure ratio
None of these
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
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
The volume of air sucked by the compressor during its suction stroke is called
Free air delivery
Compressor capacity
Swept volume
None of these
The pressure ratio of an ideal vaned compressor with increase in mass flow rate
Increases
Decreases
Remain constant
First decreases and then increases
Intercooling in gas turbines
Decreases net output but increases thermal efficiency
Increases net output but decreases thermal efficiency
Decreases net output and thermal efficiency both
Increases net output and thermal efficiency both
Turbofan engine employs
One air stream
Two or more air streams
No air stream
Solid fuel firing
The stagnation pressure rise in a centrifugal compressor takes place
In the diffuser only
In the impeller only
In the diffuser and impeller
In the inlet guide vanes only
If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix I and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity
Vi = Vo
Vt > Vo
U < Vo
V = Uo