Turbine Engine Air Systems Flashcards
How is a turbine engine cooled?
A turbine engine is cooled by the air passing over and through the engine. On a turbofan engine, a large portion of the air flows over the outside of the engine, helping to cool the various sections of the engine.
Why is it important for turbine engine to have a relatively distortion-free flow of air to the inlet of the compressor?
A uniform and steady airflow is necessary to avoid compressor stall (airflow tends to stop or reverse direction of flow) and excessive internal engine temperatures in the turbine section.
How are the high internal temperatures of a turbine engine cooled and kept under control?
A portion of the air flowing into the engine flows around the combustion chamber, and even around the internal combustion flame, to contain the flame and protect internal components of the engine.
What are baffles used for in the air flow of a turbine engine?
To direct air-cooling air to protect engine and airframe components. the combustion chamber is a specialized baffle that directs compressed air into the combustion chamber and helps contain the flame.
What is the purpose of insulation blankets in a turbine engine installation?
Although insulation blankets protect the fuselage from heat radiation, they are used primarily to reduce heat loss from the exhaust system. The reduction of heat loss improves engine performance.
What is the primary design concern of a turbine engine inlet?
The air entrance is designed to conduct incoming air to the compressor with a minimum energy loss resulting from drag or ram pressure loss; that is, the airflow of air into the compressor should be free of turbulence to achieve maximum operating efficiency. Proper inlet design contributes materially to aircraft performance by increasing the ratio of compressor discharge pressure to duct inlet pressure.
What is the compressor pressure ratio?
The ratio is the outlet pressure divided by the inlet pressure. The amount of air passing through the engine is dependent upon three factors:
1. The compressor speed (RPM).
2. The forward speed of the aircraft
3. The density of the ambient (surrounding) air.
Where is bleed air taken from on a turbine engine?
Bleed air is taken from any of the various pressure stages of the compressor. Air is often bled from the final or highest pressure stage since, at this point, pressure and air temperature are at a maximum.
What are some uses of bleed air?
-Cabin pressurization, heating and cooling
-Deicing and anti-icing equipment
-Pneumatic starting of engines
-Auxiliary drive units (ADU)
-Vortex dissipaters
How is ice prevented from forming on the nose cow, nose dome, and inlet guide vanes of a turbine eninge?
Hot compressor bleed air flows through passages in these components to elevate the surface temperatures sufficiently to prevent ice from forming.
