In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into
Atmosphere
Vacuum
Discharge nozzle
Back to the compressor
Correct Answer :
C. Discharge nozzle
Related Questions
During base load operation, the best method of controlling compressor is
Start-stop motor
Constant speed unloader
Relief valve
Variable speed
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 reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
Pressure drop across the valves
Superheating in compressor
Clearance volume and leakages
All of these
Reheating in a gas turbine
Increases the thermal efficiency
Increases the compressor work
Increases the turbine work
Decreases the thermal efficiency
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
Inter cooling in compressors
Cools the delivered air
Results in saving of power in compressing a given volume to given pressure
Is the standard practice for big compressors
Enables compression in two stages
Efficiency of gas turbine is increased by
Reheating
Inter cooling
Adding a regenerator
All of the above
The efficiency of roots blower ________ with the increase in pressure ratio.
Decreases
Increases
Does not change
None of these
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
The propulsive power of the rocket is (where v₁ = Jet velocity, and v₂ = Aircraft velocity)
(v₁² -v₂²)/2g
(v₁ - v₂)²/2g
(v₁² -v₂²)/g
(v₁ - v₂)²/g
The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is
Low
High
Same
Low/high depending on make and type
Which is false statement about advantages of multistage compressor in comparison to single stage compressor?
Less power requirement
Better mechanical balance
Less loss of air due to leakage past the cylinder
Lower volumetric efficiency
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
Which of the following statement is correct relating to rocket engines?
The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel
The stagnation conditions exist at the combustion chamber
The exit velocities of exhaust gases are much higher than those in jet engine
All of the above
The thrust of a jet propulsion power unit can be increased by
Injecting water into the compressor
Burning fuel after gas turbine
Injecting ammonia into the combustion chamber
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
Water gas is produced by
Carbonisation of coal
Passing steam over incandescent coke
Passing air and a large amount of steam over waste coal at about 65°C
Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast
The blades of gas turbine are made of
High nickel alloy
Stainless steel
Carbon steel
High alloy steel
There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would
Remain same
Decrease
Increase
None of the above
The air is delivered ________ in one revolution in case of a three lobbed rotor.
Two times
Three times
Four times
Six times
Euler's equation is applicable for
Centrifugal compressor
Axial compressor
Pumps
All of the above
The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.
Equal to
Less than
More than
None of these
In a jet propulsion
The propulsive matter is ejected from within the propelled body
The propulsive matter is caused to flow around the propelled body
Its functioning does not depend upon presence of air
None of the above
Gas turbine as compared to steam turbine
Requires less space for installation
Has compressor and combustion chamber
Has less efficiency
All of these
The maximum propulsion efficiency of a turbojet is attained at around following speed
550 km/hr
1050 km/hr
1700 km/hr
2400 km/hr
Maximum delivery pressure is a rotary air compressor is of the order of
6 kg/cm²
10 kg/cm²
16 kg/cm²
25 kg/cm²
The volume of air delivered in a medium capacity air compressor per unit time is
0.1 to 1.2 m³/s
0.15 to 5 m³/s
Above 5 m³/s
None of these
Isothermal compression efficiency can be attained by running the compressor
At very high speed
At very slow speed
At average speed
At zero speed
As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio
Increases
Decreases
Remain same
First increases and then decreases
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