021.11 TURBINE ENGINES

Question 1

In a gas turbine engine, the propelling jet is generated by (compression/expansion) of hot gases resulting in a conversion of (…) energy (pressure) into (…) ​energy (velocity).

Answer 1

In a gas turbine engine, the propelling jet is generated by (expansion) of hot gases resulting in a conversion of (potential) energy (pressure) into (kinetic) energy (velocity).

Question 2

For an reaction turbine, pressure (rises/drops/remains constant) accross the nozzle guide vanes and (rises/drops/remains constant) across the rotor blades.

Answer 2

For an reaction turbine, pressure (drops) accross the nozzle guide vanes (stators) and (drops) across the rotor blades.

Question 3

For an impulse turbine, pressure (rises/drops/remains constant) accross the nozzle guide vanes and (rises/drops/remains constant) across the rotor blades.

Answer 3

For an impulse turbine, pressure (drops) accross the nozzle guide vanes (stators) and (remains constant) across the rotor blades.

Question 4

A compressor stall is most likely to occur in a compressor designed for a (low/high) pressure ratio operating at (low/high)​ RPM.

Answer 4

A compressor stall is most likely to occur in a compressor designed for a (high) pressure ratio operating at (low) RPM.

Question 5

Put the following in correct sequence for a start of a turbine engine in flight.

• Rotation
• Fuel
• Starter
• Ignition

Answer 5

Put the following in correct sequence for a start of a turbine engine in flight.

• No starter needed in flight

1. Rotation
2. Ignition
3. Fuel

Question 6

Put the following in correct sequence for a start of a turbine engine on ground.

• Rotation
• Fuel
• Starter
• Ignition

Answer 6

Put the following in correct sequence for a start of a turbine engine on ground.

1. Starter
2. Rotation
3. Ignition
4. Fuel

Question 7

With regard to a twin spool turbofan, an abortive start (hung start) will result in N2 speed stabilising at a (lower/higher) than normal RPM and a subsequent (increase/decrease)​ in EGT.

Answer 7

With regard to a twin spool turbofan, an abortive start (hung start) will result in N2 speed stabilising at a (lower) than normal RPM and a subsequent (increase) in EGT.