Turbine Engines Flashcards

1
Q

Explain the main difference and advantage of turbo fan over turbo jet engines.

A

A turbo fan uses a fan to bypass air around the engine core and provide thrust.
This provides additional thrust without increasing fuel flow.

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2
Q

Name the major components in a gas turbine engine:

A

Air inlet.
Compressor section
Combustion section.
Turban section.
Exhaust section.
Gearbox and accessory section.

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3
Q

What determines the amount of air flow through a turbine engine?

A

The forward speed of the aircraft.
Compressor speed.
Air density.

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4
Q

Name the two types of compressors commonly used in turbine engines

A

Axial and centrifugal flow compressors.

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5
Q

Name two different methods for attaching turbine engine rotor blades to the rotor discs:

A

Dovetail type root.
Bulb type root.
Fir tree type root.

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6
Q

What is a split compressor system?

A

Split/dual/twin sport compressors are connected to the turbine section with two rotor shafts, one inside the other.

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7
Q

What are the different types of combustion chambers used in turbine engines?

A

Can.
Annular.
Can annular.
Reverse flow annular.

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8
Q

What prevents the combustion chambers from burning?

A

Cooling air along the inside of the liner.

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9
Q

What is the purpose of the interconnecting tubes attached between can type combustion chambers?

A

For flame propagation during start up.

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10
Q

What function do axial flow turbine nozzles perform?

A

They direct the mass airflow to drive the turbine rotor at a specific angle.

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11
Q

How is thermal stress relieved on a turbine disc?

A

By directing bleed air onto the face of the disc, or by grooves being cut in the disc.

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12
Q

What are carbon seals used for in turbine engines?

A

They are used as oil seals for the rotor shaft bearings.

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13
Q

What is shaft horsepower?

A

It is an indication of the torque developed by a turbo prop or turbo shaft engine.

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14
Q

Name the main components of a typical APU:

A

1) A small power turbine for power and bleed air.
2) An electrical generator.

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15
Q

When is the greatest demand placed on an APU?

A

When supplying bleed air.

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16
Q

How is an APU generally started?

A

With its own electrical starter and battery power.

17
Q

Where does an APU get its fuel supply?

A

From one of the aircraft’s main fuel tanks.

18
Q

At what speed does a gas turbine APU operate and how is the speed maintained?

A

At or near it’s rated speed.
The APU fuel control automatically adjusts fuel flow.

19
Q

What is used to prevent a heavily loaded APU from exceeding its maximum EGT?

A

A load control valve modulates the pneumatic load to maintain EGT’s within limits.

20
Q

How is an APU shut down and why is this procedure used?

A

The APU is unloaded by closing the bleed air valve, then run for a specified amount of time to allow the EGT to cool and stabilize. Typically three minutes.
An abrupt shut down could lead to thermal shock

21
Q

What powers the variable inlet guide vanes used on some APUs to regulate compressor intake airflow?

A

Fuel pressure

22
Q

What is fan blade shingling?

A

The overlapping of the mid span shrouds of the fan blade.

23
Q

When a turbofan or turbojet engine is shut down, what should a mechanic listen for during coastdown?

A

Any rubbing sound, or other unusual noises from the engine.