TURBINE Engines

Question 1

What is a rotor blade?

Answer 1

The rotating airfoil blades within the compressor section which compress and move the air through the engine.

Question 2

What is a stator vane?

Answer 2

Stationary (non-moving) airfoil blades that increase the pressure of the air by converting the rotation energy into static pressure.

The stators also prepare the air for entering the next set of rotating blades at the optimum “AOA”. They “straighten” the airflow through the engine.

Question 3

What is bleed air used for?

Answer 3

Bleed air is high pressure air usually trapped from the engine compressor section and used for cabin pressurization, heating/air conditioning, anti-ice, and engine starting.

Question 4

Where does bleed air come from?

Answer 4

Typically from one or more of the compressor stages of one of the main engines or an APU.

Question 5

Why do we have a diffuser?

Answer 5

The diffuser slows down the air from the compressor, further compressing it, and making it easier to ignite.

Question 6

Once lit, do the igniters need to keep firing or is it self sustaining?
How does a turbine engine start?

Answer 6

• Self sustaining
• 1. Compressor rotates and begins bringing in and compressing air. 2. Fuel is introduced, air/fuel mixture ignited. Expanding gases further accelerate compressors via the turbines. Becomes self sustaining.

Question 7

What are the different start malfunctions?

Answer 7

1. HOT start- too much fuel & not enough air (stop)
2. HUNG start- engine not “breathing” properly. Insufficient airflow due to high altitude, hot day, low starter RPMS
3. NO LIGHT OFF start- Too much fuel- could cause explosion.

Question 8

ITT

Answer 8

Interstate Turbine Temperature- measured between the compressor and turbines.

Question 9

EGT

Answer 9

Exhaust Gas Temperatures- usually the main engine temp gauge used to prevent heat damage to the turbine blades.

Question 10

EPR

Answer 10

Engine Pressure Ratio- the ratio of the engine output pressure to engine intake pressure.
- more EPR = more Thrust

Question 11

Flameout

Answer 11

• The flame in combustion chamber has been extinguished.
• Removing either 1. Fuel 2. Air (Oxygen) or 3. Heat will cause a flameout