Multi-stage compressors are used for……….
raising pressure ratio of the cycle.
increasing plant work output.
increasing heat transfer.
reducing work input to cycle.
Consider the following statements and select the correct one:
Steam power plant runs on Brayton cycle.
Steam power plants have higher pressure ratios than gas turbine power plants.
Thermal efficiency of gas turbine power plant is less than that of steam turbine power plant.
Working fluid in gas turbine undergoes phase change.
Using an intercooler between two stages of compressor results in which of the following?
Decreased overall work input to compressor.
Increased overall work input to compressor.
Overall work input to compressor remains same.
May increase or decrease the overall work input to compressor.
Propulsive efficiency is defined as ratio of……….
input fuel energy to change in kinetic energy.
change in kinetic energy to input fuel energy.
change in kinetic energy to thrust power.
thrust power to change in kinetic energy.
How does propulsive efficiency vary with increasing flight speed for turboprop engine?
Increases monotonically
Decreases monotonically
First increases then decreases
First decreases then increases
The working fluid in a turbine is in……….
the form of air and water mixture.
a single phase.
two phases.
three phases.
Only rockets can be propelled to space because……….
they have high propulsive efficiency.
they can work on different type of fuels
they are not air-breathing engines.
they can generate high thrust.
In a turbo-jet engine, the combustion products after passing through the gas turbine are discharged into……….
vacuum.
atmosphere.
back to the compressor.
discharge nozzle.
Ram compression in turbojet involves..........
increasing speed of inlet air.
compression of inlet air.
reduction of speed of incoming air and conversion of part of it into pressure energy.
lost work.
An aircraft engine has incoming air at a velocity of 280 m/s and air exhaust velocity of 650 m/s. The propulsive efficiency of the aircraft is……….
0.60
0.51
0.57
0.45
A gas turbine engine has a………. overall efficiency and a………. mechanical efficiency than a reciprocating engine.
higher. lower
lower, higher
lower, lower
higher, higher
For a Brayton cycle with maximum work output having a cycle pressure ratio of 7 and compressor inlet temperature of 310 K, the turbine inlet temperature will be ……….
540 K
737 K
942 K
561 K
Choose the correct order of the aircraft engines in order of their increasing speeds.
Turbo prop, piston prop, ramjet
Ramjet, turbofan, turbojet
Turbojet, turbofan, turbo prop
Piston prop, turbojet, ramjet