Turbine Engines

Question 1

What are the two basic sections of a turbine engine?

Answer 1

Hot and Cold sections

Question 2

What are the two basic types of compressors that are used in aircraft turbine engines?

Answer 2

Axial Flow and Centrifugal

Question 3

What is the purpose of the stators in an axial flow compressor?

Answer 3

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

Question 4

What are the three types of combustors used on aircraft turbine engines?

Answer 4

Can, Annular, Can-Annular

Question 5

How many igniters are there normally in an aircraft turbine engine?

Answer 5

Two

Question 6

What is the main purpose of the turbine nozzle in an aircraft turbine engine?

Answer 6

The turbine nozzles direct the hot gases as they leave the combustors so they will turn the turbine wheel with max efficiency

Question 7

What is meant by a free-turbine turboshaft engine?

Answer 7

A turboshaft engine that has a turbine wheel, or stage of turbine wheels 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.

Question 8

Why do some axial-flow turbine engines have more than one set of turbines and compressors?

Answer 8

A two-speed turbine engine has a low pressure and high pressure compressor, each driven by its own turbine. The two independent systems operate at the speed at which they are most efficient.

Question 9

What kind of bearings are used to support the rotor shaft of an aircraft turbine engine?

Answer 9

Antifriction bearings, such as ball bearings or roller bearings

Question 10

What is meant by a turbofan engine?

Answer 10

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

Question 11

Where can you find the limits of repair allowed for the compressor blades of an aircraft turbine engine?

Answer 11

In the FAA-approved service manual issued by the manufacturer of the engine

Question 12

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?

Answer 12

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

Question 13

What is meant by a hung start in a turbine engine?

Answer 13

A start in which ignition occurs, but the engine does not accelerate to a self-sustaining speed

Question 14

What is meant by a hot start in a turbine engine?

Answer 14

A start in which ignition occurs, but the internal temperatures go high enough that they can damage the engine.

Question 15

What is meant by creep of the turbine blades?

Answer 15

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

Question 16

How is the compressor of a turbine engine cleaned?

Answer 16

An emulsion-type cleaner is sprayed through the engine while it is being motored by the starter or operated at a low speed. The wash is followed by a clean water rinse.
More vigorous cleaning is done by injecting a mild abrasive, such as ground-up apricot pits or walnut shells, into the engine while operating at low speed

Question 17

Where is the water injected into a turbine engine for cooling purposes?

Answer 17

Into the compressor inlet and into the engine diffuser case

Question 18

What is the function of the interconnect tubes between the cans of a turbine engine that uses can type compressors?

Answer 18

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

Question 19

What are two types of thrust reversers that are used on turbojet engines?

Answer 19

The mechanical blockage-type and the aerodynamic blockage type

Question 20

What is meant by trimming a turbojet engine?

Answer 20

Adjusting the fuel control to get the correct idling and maximum thrust RPM