Turbine Engines Flashcards
Define the term “thermal efficiency” in regards to aircraft engines.
The ratio of net work produced by the engine to the chemical energy supplied in the form of fuel
What are the major components of a typical gas turbine engine?
Air inlet, compression section, combustion section, turbine section, exhaust section, and accessory section
What are the two principle types of compressors used in turbojet aircraft?
Centrifugal and Axial flow
What are the four combustion chamber systems?
Can, Annular, Can-Annular, Reverse Flow Annular
What is the purpose of the interconnector tubes between can type combustion chambers?
To spread the flame to the combustion chambers that are not equipped with igniter plugs during engine starting
What prevents burning of the liner walls in a can type combustion chamber?
Louvers are provided along the axial length of the liners to direct a cooling layer of air along the inside wall of the liner
What types of damage may be found when inspecting compressor blades?
Burns, Burrs, Cracks, Dents, Galling, Gouges, Pitting, Scratches
What is the location and function of the diffuser section in a turbine engine?
Located between the compressor section and burner cans to change the high velocity compressor discharge air to static pressure
Where are stress rupture cracks most likely to occur on turbine blades?
Across the leading or trailing edge of the blades
How are compressor blades attached to a disk-type rotor?
By either bulb-type, fir-tree, or dove tail type roots. Blades are then locked by means of screws, peening, locking wires, pins, or keys
What is the purpose of the nozzle diaphragm or turbine nozzle?
The turbine nozzle prepares the combustion mass airflow to drive the turbine rotor
What is the major difference between turboprop and turbojet engines?
A turboprop engine usually has more turbine stages, and the turbine must also drive a propeller
What is a turbofan engine?
It is the same as a turboprop, except that the propeller is replaced with a duct-enclosed axial flow fan
What is the starting sequence for a turbine engine?
Rotate compressor with starter
Turn the ignition on
Open the engine fuel valve
What is the effect of air density on the thrust of a turbine engine?
As air density increases thrust increases
What are the two most common types of thrust reversers?
Mechanical and Aerodynamic Blockage
What is a split compressor system in a turbine engine?
It requires two concentric shafts joining the turbine stages to their respective compressors
What is one method of relieving thermal stress on a turbine disk?
Direct cooling bleed air back onto the face of the disk
What may be the indicators if a turbojet engine is out of trim?
High Exhaust Gas Temperature
What does it mean when you have high exhaust gas temperature, high fuel flow, and low thrust or power?
Pending engine failure or low compression
What is a free turbine?
A turbine wheel that, rather than driving the compressor rotor, drives a propeller or helicopter transmission
What is the main purpose of thrust reversers?
Slowing the aircraft down to effective braking speeds
What are the advantages of turbofan engines over turbojet engines?
Turbofan engines provide additional thrust without increasing fuel flow
What methods are commonly used to accomplish turbine engine compressor field cleaning?
Fluid wash and Abrasive Grit Blast
