A rocket works with maximum overall efficiency when air craft velocity is equal to the :
A. jet velocity
B. twice the jet velocity
C. half the jet velocity
D. average of the jet velocity
The main purpose of reheating in gas turbine is to :
A. increase temperature
B. reduce turbine size
C. increase power output
D. increase speed
E. increase pressure ratio
Work ratio of a gas turbine may be improved by :
A. decreasing the compression work
B. increasing the compression work
C. increasing the turbine work
D. decreasing the turbine work
E. A. and C. above
In which case the air-fuel ratio is likely to be maximum :
A. 2-stroke engine
B. 4-stroke petrol engine
C. 4-stroke diesel engine
D. multi-cylinder engine
E. gas turbine
High air-fuel ratio is used in gas turbines :
A. to increase the output
B. to increase the efficiency
C. to save fuel
D. to reduce the exit temperature
In jet engines the compression ratio :
A. varies as square root of the speed
B. Varies linearly to the speed
C. varies as square of the speed
D. varies as cube of the speed
Air-fuel ratio in a jet engine will be of the order of :
A. 10: 1
B. 15: 1
C. 20 : 1
D. 60 : 1
The effective power of gas turbines is increased by adding the following in compressor :
A. ammonia and water vapour
B. carbon dioxide
C. nitrogen
D. hydrogen
E. none of the above
The main purpose of reheating in gas turbine is to :
A. increase temperature
B. reduce turbine size
C. increase power output
D. increase speed
