M15.3 Inlet Flashcards
What is the primary function of the engine inlet of a turbine engine?
To provide a relatively distortion-free airflow to the inlet of the compressor in the required quantity.
What are Inlet Guide Vanes (IGV) used for?
To straighten the airflow and direct it into the first stages of the compressor.
What can excessive internal engine temperatures in the turbine section lead to?
Compressor stall.
Is the air-inlet duct considered part of the engine or the airframe?
It is considered an airframe part.
How does the air intake size of gas turbine engines compare to reciprocating engines?
Gas turbine engines consume considerably more airflow and have a much larger air entrance passage.
What can result from inefficiencies of the inlet duct?
Performance losses through other components of the engine.
What is ‘ram recovery’ in the context of aircraft speed and thrust?
It compensates for losses caused by increases in speed.
What causes an air pressure drop in the engine inlet?
Friction of air along both sides of the duct and bends in the duct system.
What is a divided-entrance duct primarily used for?
High-speed, single, or twin-engine military aircraft.
What is one major drawback of a divided duct system?
Designing an entrance duct of reasonable length with as few bends as possible.
What is a variable-geometry duct designed to do?
Provide the correct amount of air to the engine inlet and reduce airflow velocity.
True or False: Airflow through the engine must always be less than Mach 1.
True.
What is the purpose of a shock wave in the airstream of supersonic aircraft?
To create a thin region of discontinuity that diffuses the airflow and decreases velocity.
What is a compressor inlet screen used for?
To prevent the engine from ingesting items that can be drawn in the intake.
What is a bellmouth inlet primarily used for?
Obtaining very high aerodynamic efficiency during engine testing.
What is the function of a ducted arrangement in turboprop engines?
To optimize airflow and aerodynamic characteristics.
How does icing affect engine performance?
It can disturb airflow, leading to reduced performance and potential compressor stall.
What are the two common types of engine ice protection systems?
- Bleed Air
- Electrical Heating (thermal)
What is the role of anti-icing valves in bleed air systems?
To protect against overpressurization and limit bleed air loss.
What happens when an anti-ice valve opens?
Hot air enters the anti-ice duct and sprays into the engine cowling.
What is an electro-thermal anti-icing system primarily used in?
Smaller turboprop and turboshaft engines.
Fill in the blank: The main function of an inlet duct is to provide the correct amount of air to the _______.
[engine inlet]
What is the effect of ice on the engine inlet’s airflow?
It can lead to a disturbed airflow that reduces performance.
What is the purpose of using warm bleed air in anti-icing systems?
To keep the engine inlet free of ice during ground and flight operations.
What controls the flow of hot air to the engine inlet when anti-icing is turned on?
The EEC controls the flow of hot air based on inputs from the aircraft and engine sensors.
What type of anti-icing systems do smaller turboprop and turboshaft engines typically use?
Electric heat strip systems, classified as electro-thermal anti-icing systems.
How are electric heat strip systems constructed?
They are constructed of electrical resistance wire embedded in layers of reinforced neoprene materials.
Where are the electric heat strips primarily located?
At the lip of the nacelle inlet.
When do electro-thermal anti-icing systems operate?
They operate only when the engine is running.
What can happen if electric heat strips operate without air passing over them?
They can overheat and potentially cause damage to the engine.
What is the first step in troubleshooting if ice forms in the inlet with the anti-icing system turned ON?
Verify the correct power source at the valve.
What should be checked if compressor stalls occur at high power settings with the anti-icing system OFF?
Ensure that ambient conditions are within operational guidelines.
What is the remedy for an engine unable to attain full power at EGT limit?
Verify the correct power source at the valve and check for leak-through.
What should be done if the air regulator is stuck fully open?
Bench check for the correct operation of the bimetallic coil.
What might cause fluctuating EGT and engine speed?
Anti-icing valves intermittently open when the system is off.
What should be checked if there is an EPR rise during flight?
Check for ice build-up causing a decrease in inlet pressure.
Fill in the blank: The anti-icing system is designed to operate only when the _______.
[engine is running]
True or False: Electric heat strip systems are designed to operate continuously regardless of engine status.
False
