DGCA & EASA Module 15 : Part-15 Engine Power Augmentation Systems Question

DGCA & EASA Module 15 : Part-15 Engine Power Augmentation Systems Question-Answer


1. When reheat is used, E.P.R.
A. is reduced.
B. remains constant.
C. is increased.
Ans : remains constant.
Explanation: Rolls Royce The jet engine page 175 states that as P6 increases in the jet pipe the nozzles are opened to reduce P6 back to its normal value.


2. When reheat is selected and in operation, the mass gas flow.
A. decreases.
B. remains the same.
C. increases.
Ans : remains the same.
Explanation: NIL.

3. Screech liners in the afterburning jet pipe.
A. prevent unstable combustion.
B. prevent cyclic vibrations of large amplitude.
C. acts as noise suppressors.
Ans : prevent cyclic vibrations of large amplitude.
Explanation: NIL.

4. Water methanol for cooling is injected into the.
A. compressor inlet or outlet.
B. engine hot zone.
C. combustion chamber.
Ans : compressor inlet or outlet.
Explanation: Jepperson Gas Turbine Powerplants Page 7-41 refers.

5. On an injection system.
A. methanol is injected neat.
B. town water/methanol is injected.
C. demineralized water/methanol is injected.
Ans : demineralized water/methanol is injected.
Explanation: Jepperson Gas Turbine Powerplants Page 7-41 refers.

6. When using water methanol in an axial flow compressor, it is injected into the.
A. compressor inlet or burner section.
B. burner.
C. intake.
Ans : compressor inlet or burner section.
Explanation: Jepperson Gas Turbine Powerplant Fig 7-32.

7. The main reason for adding methanol to the water is to.
A. temper the cooling effect of the water to prevent distortion.
B. supply the additional heat required.
C. prevent mixture freezing.
Ans : prevent mixture freezing.
Explanation: Rolls Royce The Jet Engine page 181 refers.

8. The primary purpose of water injection is to.
A. decrease mass airflow.
B. increase the calorific value of the fuel.
C. cool the turbine.
Ans : cool the turbine.
Explanation: Notice that the answers did not include 'increase mass airflow'. Cooling the turbine is the primary purpose o=if the water is injected in the combustor outlet manifold.

9. Water used in a thrust augmentation system should be demineralised to prevent.
A. blocking the jet.
B. carbon formation.
C. fouling the blades and vanes.
Ans : fouling the blades and vanes.
Explanation: NIL.

10. The quantity of water usually carried by an aircraft equipped with water injection is enough for.
A. three take-offs.
B. one take-off.
C. two take-offs.
Ans : one take-off.
Explanation: Jeppesen Gas Turbine Powerplants Page 7-41 refers.

11. Water methanol injection will increase thrust by up to.
A. 70%.
B. 50%.
C. 30%.
Ans : 30%.
Explanation: Jeppesen Aircraft Gas Turbine Powerplant page 7-41 shows 10-15% so 30% is nearest.

12. Injection of water/methanol into compressor inlet causes.
A. increase in power due to the burning of methanol alone.
B. increase in power without the need for burning extra fuel.
C. increased efficiency of the engine due to reduced icing in the airflow.
Ans : increase in power without the need for burning extra fuel.
Explanation: Jeppesen Aircraft gas Turbine Power plant page 7-41 refers.

13. Reheat is the term used to describe.
A. adding fuel in the exhaust section.
B. adding of fuel in the turbine section.
C. adding of fuel in the compressor section.
Ans : adding fuel in the exhaust section.
Explanation: Rolls Royce The Jet Engine Page 169 refers.

14. Water/methanol is injected.
A. at high temperatures.
B. at high temperature, at high altitudes.
C. at high temperatures or high altitudes.
Ans : at high temperatures or high altitudes.
Explanation: Jeppesen aircraft gas turbine Powerplants Page 7-39 refers.

15. The reheat ignition system which incorporates a platinum/rhodium element is known as.
A. catalytic ignition.
B. hot-shot ignition system.
C. spark ignition system.
Ans : catalytic ignition.
Explanation: fuel sprayed on to the catalytic element heats up and ignites.

16. Water or water/methanol injected into the combustion chamber inlet increases.
A. mass airflow through the turbine.
B. combustion chamber outlet temperatures.
C. fuel to air ratio by up to 20%.
Ans : mass airflow through the turbine.
Explanation: Jeppesen Gas turbine Power plant page 7-41 refers.

17. Methanol is added to water when augmenting thrust in order to.
A. reclaim lost pressure at the compressor.
B. increase the density of air entering the compressor.
C. reclaim lost heat at the turbines.
Ans : reclaim lost heat at the turbines.
Explanation: Methanol burns, but its heat output is low. It's prime purpose is to act as an antifreeze in the water.

18. Afterburning is initiated in order to.
A. heat the exhaust to prevent choking at subsonic gas velocities.
B. burn off the fuel that is not combusted in the combustion section.
C. increase the local speed of sound at the jet nozzle.
Ans : increase the local speed of sound at the jet nozzle.
Explanation: A faster SoS allows for greater momentum thrust at the exhaust nozzle.

19. How is the flame stabilised in the reheat system of a gas turbine engine?.
A. By creating a greater potential between inlet & jet pipe temperatures.
B. By ensuring that the gas velocity is greater than the flame velocity.
C. By ensuring that the flame velocity is greater than the gas velocity.
Ans : By ensuring that the gas velocity is greater than the flame velocity.
Explanation: The guttering in the reheat manifolds allows the flame to stabilise at the point.

20. During operation of the engine equipped with water injection system, the metering of the coolant to the system is.
A. selected by the pilot.
B. due to atmospheric pressure.
C. due to altitude change.
Ans : selected by the pilot.
Explanation: Water injection is used on take off as required by the pilot.

21. Water methanol injection is used.
A. at high altitude take off conditions only.
B. at a combination of higher than normal air temperatures and high altitude take off conditions.
C. at higher than normal ambient air temperatures only.
Ans : at higher than normal ambient air temperatures only.
Explanation: Water Methanol adds to the weight of the air thus compensating for reduced density.



Click Here For : DGCA & EASA Module 15 : Part-16 Turbo-prop,Turbo-Shaft Engine & Auxiliary Power Units (APUs) Question

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