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Power-Plant
TURBINE ENGINES
Question | Answer |
---|---|
What are the two basic sections of a turbine engine? | The hot section and the cold section. |
What are the two basic types of compressors that are used in aircraft turbine engines? | Axial-flow and centrifugal. |
What is the purpose of the stators in an axial-flow compressor? | The stators convert some velocity energy into pressure energy and change the direction of the air so it is proper for the next stage of rotors. |
What are three types of combustors used on aircraft turbine engines? | Can-type, annular-type, and can-annular-type. |
How many igniters are there normally in an aircraft turbine engine? | Two. |
What is the main purpose of the turbine nozzle in an aircraft turbine engine? | The turbine nozzle directs the hot gases as they leave the combustors so they will turn the turbine wheel with maximum efficiency. |
What is meant by a free-turbine turboshaft engine? | A turboshaft engine that has a turbine wheel that is not used to drive the compressor of the gas generator section of the engine. This free turbine drives the propeller in a turboprop engine or the transmission and rotor of a helicopter. |
Why do some axial-flow turbine engines have more than one set of turbines and compressors? | A two-spool turbine engine has a low-pressure and a high-pressure compressor, each driven by its own turbine. The two independent systems operate at the speed at which they are most efficient. |
What kind of bearings are used to support the rotor shaft of an aircraft turbine engine? | Anti-friction bearings, such as ball bearings or roller bearings. |
What is meant by a turbofan engine? | An axial-flow turbine engine in which the first stage of compressor blades are lengthened, so they can force air around the outside of the gas generator portion of the engine. |
Where can you find the limits of repair allowed for the compressor blades of an aircraft turbine engine? | In the FAA-approved service manual issued by the manufacturer of the engine. |
Why is it important that a turbojet engine be allowed to cool before it is shut down after it has been operated at a high power setting? | If the engine is shut down while it is hot, there is a possibility that the shroud will contract around the turbine wheel and seize the rotor. |
What is meant by a hung start in a turbine engine? | A start in which ignition occurs, but the engine does not accelerate to a self-sustaining speed. |
What is meant by a hot start in a turbine engine? | A start in which ignition occurs, but the internal temperatures go high enough that they can damage the engine. |
What is meant by creep of the turbine blades? | A condition of permanent elongation of the turbine blades. Creep is caused by the high temperatures and the high centrifugal loading imposed on the blades. |
How is the compressor of a turbine engine cleaned? | Emulsion-type cleaner sprayed through the engine while it is being motored by the starter/operated at a low speed. Followed by a clean water rinse. Vigorous cleaning is done by injecting a ground-up apricot pits or walnut shells, operating at low speed. |
Where is water injected into a turbine engine for cooling purposes? | Into the compressor inlet and into the engine diffuser case. |
At what point in a turbine engine is the temperature the highest? | At the inlet to the high-pressure turbine. |
What is the function of the interconnect tubes between the cans of a turbine engine that uses can-type combustors? | These tubes allow the flame to travel from the cans that contain the igniters to all of the other cans when the engine is being started. |
What are two types of thrust reversers that are used on turbojet engines? | The mechanical blockage-type and the aerodynamic blockage-type. |
What is meant by trimming a turbojet engine? | Adjusting the fuel control to get the correct idling and maximum-thrust RPM. |