Aircraft Engines

Question 1

Thrust

Answer 1

Force needed to overcome drag.

Question 2

Gas Turbine Engine

Answer 2

Develops thrust by burning a combustible fuel-air mixture and changing energy of expanding gases into propulsive force. Has a four-cycle process.

Question 3

4-Cycle Process

Answer 3

Intake, Compression, Combustion, and Exhaust.

Question 4

Engine Sections

Answer 4

Air Inlet, Compressor, Diffuser, Combustion, Turbine, Exhaust, and Accessory Section.

Question 5

Air Inlet

Answer 5

Designed to channel incoming air into the compressor with minimum energy loss from ram or drag effects.

Question 6

Two Functions of Air Inlet

Answer 6

First, recovers as much total pressure as possible and delivers it to the front of the engine. Secondly, delivers air to the compressor inlet with a minimum of turbulence and pressure variations.

Question 7

Compressor

Answer 7

Primary function is to supply air in sufficient quantity to produce required engine thrust(power).

Question 8

Main element Of a compressor

Answer 8

Rotor and Stator

Question 9

Rotor

Answer 9

Blades fixed on a spindle, compresses air at each stage and accelerated it rearward.

Question 10

Stator

Answer 10

Stationary blades fixed within the engine, act as diffusers at each stage, partially converting high velocity to pressure.

Question 11

Diffuser

Answer 11

Slows down and evenly spreads out the air for combustion process.

Question 12

Combustion

Answer 12

Houses the fuel nozzles and igniter plugs.

Question 13

Fuel Nozzles

Answer 13

Surrounds the combustion chamber and evenly sprays fuel throughout the chamber.

Question 14

Turbine

Answer 14

Transforms a portion of the energy of the exhaust gases into mechanical energy to drive the compressor and accessories. Absorbs 60% to 80% of total pressure energy from exhaust gases.

Question 15

Turbine Assembly

Answer 15

Located aft of the combustion chamber, consists of two basic parts; rotor and stator. Construction is similar to compressor.

Question 16

Stator(TA)

Answer 16

“Turbine Guide Vanes”. Discharges gas at extremely high speed directly onto the rotor assembly. Converts pressure energy into mechanical energy.

Question 17

Rotor(TA)

Answer 17

“Turbine Wheel”. Blades attached to rotating disk, which is attached to the main power-transmitting shaft of the engine.

Question 18

Engine Rotor Assembly

Answer 18

Combination of the compressor and turbine rotors on a common shaft.

Question 19

Exhaust

Answer 19

Direct the flow of hot gases leaving the turbine section.

Question 20

Accessory

Answer 20

Primarily, it provides space for accessories necessary for operation and control of the engine. Generators and fluid pumps are mounted.

Question 21

Fluid Pumps

Answer 21

Consists of Hydraulic, Oil, and fuel pumps.

Question 22

Types of Jet Engines

Answer 22

Turbojet, Turboprop, and Turbofan.

Question 23

Turbojet

Answer 23

Straight gas turbine engine that gets its thrust by accelerating a mass of air through the engine. All thrust produced occurs within the engine.

Question 24

Advantages of Turbojet

Answer 24

Best at high speeds for aircraft like fighter jets.

Question 25

Disadvantages of Turbojet

Answer 25

Cannot produce exceptionally high thrust at low altitudes and speeds.

Question 26

Turboprop

Answer 26

Combines thrust developed by propeller and thrust produced by the exhaust gases at the exhaust nozzle. Take the max possible gas energy from gas steam. 90% converts to shaft horsepower driving propeller reduction gears and accessories. 10% produces jet thrust as gases exit exhaust nozzle.

Question 27

Extension Shaft Assembly

Answer 27

Transmits power from the engine to the reduction gear assembly(gearbox).

Question 28

Reduction Gear Assembly

Answer 28

Reduces high rotation speed if the turbines to a suitable propeller shaft speed. Read case is used for mounting accessories.

Question 29

Advantages of Turboprop

Answer 29

Develop high thrust at low altitudes, ideal for lifting heavy loads off short or medium length runways.

Question 30

Disadvantages of Turboprop

Answer 30

Propeller efficiency drops off as airspeed and altitudes increase.

Question 31

Turbofan

Answer 31

Similar to Turboprop except that an enclosed axial flow fan replaces the geared propeller. Produce between 30% and 85% of total thrust. Fan air exhausts through fan discharge nozzle.

Question 32

Advantages of Turbofan

Answer 32

Combines good operating efficiency and high thrust capability of the turboprop with the high speed, high altitude capability of the turbojet. Higher and more efficient cruise thrust and lower fuel consumption. Less weight, noise.

Question 33

Disadvantages of Turbofan

Answer 33

No major disadvantages, almost always power plant for all large conventional military aircraft for this reason.

Question 34

Engine Ratings

Answer 34

Represent thrust that an engine develops during various operating conditions such as takeoff, climb, and cruise. Manufacturer establishes rating in terms of pounds of thrust.

Question 35

3 conditions which influence power input of engines

Answer 35

1) Temperature of Atmosphere- High Temp=Less Power/ Low Temp= More Power 2) Pressure of Atmosphere- Low Pressure=Less Power/ High Pressure=More Power 3) Bleed Air extracted from engine.

Question 36

Flat Related

Answer 36

Refers to the ability of the engine to produce a constant maximum thrust over a wide temperature range.