A compressor at high altitudes will require ________ power.
Same
Less
More
None of these
Correct Answer :
B. Less
Related Questions
The maximum temperature in a gas turbine is
200°C
500°C
700°C
1000°C
In a centrifugal compressor, the flow of air is ________ to the axis of compressor.
Parallel
Perpendicular
Inclined
None of these
If infinite number of heaters be used in a gas turbine, then expansion process in turbine approaches
Isothermal
Isentropic
Adiabatic
Isochoric
Work ratio of a gas turbine may be improved by
Decreasing the compression work
Increasing the compression work
Increasing the turbine work
Both (A) and (C) above
The minimum work required for a three stage reciprocating air compressor is ________ the work required for each stage.
Equal to
Double
Three times
Six times
In air compressors, free air delivery means the
Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions
Volume of air delivered by the compressor
Volume of air sucked by the compressor during its suction stroke
None of the above
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
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 performance of air compressor at high altitudes will be ________ as compared to that at sea level.
Same
Lower
Higher
None of these
Turbofan engine employs
One air stream
Two or more air streams
No air stream
Solid fuel firing
After-cooler is used to
Cool the air
Decrease the delivery temperature for ease in handling
Cause moisture and oil vapour to drop out
Reduce volume
A rocket engine uses ________ for the combustion of its fuel.
Surrounding air
Compressed atmospheric air
Its own oxygen
None of these
The clearance volume of the air compressor is kept minimum because
It allows maximum compression to be achieved
It greatly affects volumetric efficiency
It results in minimum work
It permits isothermal compression
A rotary compressor is driven by an
Electric motor
Engine
Either (A) or (B)
None of these
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
Which of the following statement is correct?
The ratio of the discharge pressure to the inlet pressure of air is called compressor efficiency
The compression ratio for the compressor is always greater than unity
The compressor capacity is the ratio of workdone per cycle to the stroke volume
During isothermal compression of air, the workdone in a compressor is maximum
The efficiency of a jet engine is higher at
Low speeds
High speeds
Low altitudes
High altitudes
It is not possible to use closed gas turbine cycle in aeronautical engines because
It is inefficient
It is bulky
It requires cooling water for its operation
None of the above
With the decrease in compression ratio, the volumetric efficiency
Does not change
Increases
Decreases
First decrease and then increase
The ratio of specific weight/h.p. of gas turbine and I.C engines may be typically of the order of
1 : 1
2 : 1
4 : 1
1 : 6
The fuel consumption in gas turbines is accounted for by
Lower heating value
Higher heating value
Heating value
Higher calorific value
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 volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation
0.1 %
0.5 %
1.0 %
5 %
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
To avoid moisture troubles, the branch connections from compressed air lines should be taken from
Top side of main
Bottom side of main
Left side of main
Right side of main
Fighter bombers use following type of engine
Turbojet
Turbo-propeller
Rocket
Ramjet
The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of
75 %
85 %
90 %
99 %
A jet engine has
No propeller
Propeller in front
Propeller at back
Propeller on the top
A turboprop is preferred to turbojet because
It has high propulsive efficiency at high speeds
It can fly at supersonic speeds
It can fly at high elevations
It has high power for take off
An air compressor may be controlled by
Throttle control
Clearance control
Blow off control
Any one of the above