GAS TURBIN INTRODUCTION – Air – DGCA Question Bank For Politics

#1. When gases pass through a convergent duct their:

Velocity and temperature increase and their pressure decreases.

Their velocity increases and their temperature and pressure decrease.

Their velocity decreases and their temperature and pressure increase.

They expand adiabatically.

#2. Select the correct order of best propulsive efficiency, from low to high airspeed

High by-pass ratio turbo jet, Low by-pass ratio turbo jet, Pure turbo jet, Turbo-prop.

Low by-pass ratio turbo jet, Pure turbo jet, Turbo-prop, High by-pass ratio turbo jet.

Pure turbo jet, Turbo-prop, High by-pass ratio turbo jet, Low by-pass ratio turbo jet.

Turbo-prop, High by-pass ratio turbo jet, Low by-pass ratio turbo jet, Pure turbo jet.

#3. The highest pressure in a gas turbine engine occurs:

Between the compressor and the combustion chamber.

In the combustion chamber.

In the jet pipe.

At the P1 probe.

#4. In a turbo-fan engine, the fan speed is controlled by:

A reduction gear.

A waste gate.

The turbine.

Varying the pitch.

#5. In a high ratio by-pass engine:

All of the air goes through both the low and high pressure compressors.

Not all the air goes through the high pressure compressor.

Not all the air goes through the low pressure compressor.

All the air goes through the high pressure compressor.

#6. Modular construction:

Is only used on turbo-prop engines.

Cannot be used on high ratio engines.

Has a weight saving function.

Enables malfunctioning sections of the engine to be changed without changing the whole engine.

#7. Gas turbine engine efficiency increases with:

An increase in volumetric efficiency.

An increase in ambient temperature.

A decrease in ambient temperature.

A decrease in ambient air pressure.

#8. On a cold day, the idle speed of a gas turbine engine which has no fuel control unit compensation:

Is unaffected by temperature.

Will increase.

Will decrease.

Will increase by no more than 4%.

#9. The By-Pass Ratio of an engine is the ratio of:

Primary air to tertiary air.

Cold stream air to that flowing through the hot core of the engine.

Exhaust gas pressure to air intake pressure.

Primary air to secondary air.

#10. The Gas Turbine Engine uses the principle of:

Newton’s Third Law of motion.

Creating thrust equal to the weight of the aircraft.

Expelling air at the same speed as that of the aircraft.

The fluid flywheel.

#11. The addition of heat in a combustion chamber allows a:

Large expansion at a substantially constant pressure.

Large expansion at a constant volume.

Large expansion at a decreasing static pressure.

Minimum expansion at a constant volume.

#12. In a divergent duct:

The pressure decreases and the temperature and velocity increases.

The pressure, velocity and temperature increases.

The pressure temperature increases and the velocity decreases.

The pressure decreases, the temperature increases and the velocity remains constant.

#13. In a twin spool engine:

The L.P. compressor is connected to the H.P. compressor.

The H.P. turbine is connected to the L.P. compressor, the L.P. turbine is connected to the H.P. compressor.

The L.P. turbine is connected to the L.P. compressor, the H.P. turbine is connected to the H.P. compressor.

The H.P. turbine is connected to the L.P. turbine, the H.P. compressor is connected to the L.P. compressor.

#14. A By-Pass Ratio of 5:1 means that:

5 pounds of air is by-passed for every 10 pounds entering the engine intake.

5 pounds of goes through the H.P. compressor for every 10 pounds that enters the intake.

10 pounds of air goes through the by-pass for every 5 pounds that enters the intake.

5 pounds of air is by-passed for every 1 pound that goes through the hot core of the engine.

#15. Aft of the compressor:

The velocity of the airflow remains the same.

The velocity of the airflow decreases before the combustion chamber.

The velocity increases before the combustion chamber.

The air pressure decreases before the combustion chamber.

#16. The fan in a ducted fan engine, is driven by:

The high pressure turbine.

The rearmost turbine.

The intermediate pressure turbine.

All of the above.

#17. In a by-pass engine, the by-pass air:

Increases the air mass flow and therefore increases the propulsive efficiency.

Cools the combustion chamber and therefore increases the thermal efficiency.

Reduces the air mass flow and therefore increases the propulsive efficiency.

Increases the air mass flow and therefore reduces the propulsive efficiency.

#18. The majority of the thrust of a:

Turbo-fan engine comes from the turbine exhaust.

Turbo-prop engine comes from the turbine exhaust.

Turbo-shaft engine comes from the free power turbine exhaust.

Turbo-fan engine comes from the by-pass air.

#19. A Pure Turbo-Jet engine gives:

A small acceleration to a large mass of air.

A large acceleration to a large mass of air.

A small acceleration to a small mass of air.

A large acceleration to a small mass of air.

#20. During the Brayton cycle, combustion takes place:

Continuously.

Once every revolution.

Once every other revolution.

Only during the start cycle.

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