apu and turbine lecture

Turbine engine sections

The six main sections in sequence are: Compression, Aircraft, Exhaust, Accessories.

Ground Power Unit (GPU)

Supplies electrical power to the aircraft.

Starter Motor

Receives power from the GPU to start the rotation of the accessory section of the APU.

Drive Shaft

Part of the APU that rotates components including the loading compressor, power compressor, turbine, and AC generator.

Load Compressor

Increases air pressure before directing it to the pneumatic system.

Bleed Control Valve

Directs the compressed air from the load compressor to various systems.

Combustion Section

Where fuel and air mix for combustion; it can consist of multiple cans.

Igniter Plugs

Devices that create a spark to ignite the fuel-air mixture in the combustion chamber.

Turbine Inlet Temperature (TIT)

The ultimate limiting factor of turbine temperature, indicated by a thermocouple at the turbine inlet.

Compression Ratio

The ratio of the pressure at the outlet to the pressure at the inlet of a compressor.

Air Density Factors

Temperature, pressure, and altitude that determine the density of air entering the turbine engine.

Variable Inlet Guide Vanes (IGVs)

Used to direct airflow into the compressor stages; can be static or adjusted by fuel pressure.

Thrust Ratio Categories

Low, Medium, High, and Ultra High bypass ratios based on airflow and thrust generation.

Exhaust Section Units

Includes the cone, which helps in uniform exhaust gesture and pressure for thrust generation.

EGT (Exhaust Gas Temperature)

Measures the temperature of exhaust gases; indicates fuel consumption and engine performance.

Labyrinth Seal

Seals designed to separate oil and air in turbine engines, preventing leakage.

N1 and N2 Turbines

Components that rotate compressors and additional rotor systems; engage in various engine processes.

Pneumatic Starter

Uses high-pressure air to rotate the turbine impeller in accessory sections.

Fuel Control Unit

Monitors and meters fuel delivery to the combustion chamber.

Supersonic airflow

Occurs when the airflow velocity exceeds the speed of sound, requiring specific design adaptations.

Turbojet vs Turbofan

Turbojets burn more fuel with lower mass airflow; turbofans are more efficient with larger bypass air.

Compressor Stages

Composed of rotors and stators; determine the compression ratios within an axial or centrifugal compressor.

Vacuum Effect

Created by rotating components that draws air into the system; necessary for starting engines.

Cooling System

Utilizes compressed air for maintaining turbine temperatures within safe limits.

Accessory Gear Driven Section

Rotates various accessories of the turbine engine such as fuel pumps and hydraulic pumps.