15.1 Fundamentals

Question 1

What is the purpose of the compressor?

Answer 1

To increase static pressure.

Question 2

What is dynamic pressure also known as?

Answer 2

Velocity.

Question 3

What is the purpose of the combustion chamber?

Answer 3

To increase energy.

Question 4

How does the combustion chamber increase energy?

Answer 4

By adding fuel.

Question 5

What happens to the air after the combustion chamber?

Answer 5

It is directed to the turbines and absorbs more energy which turns the shaft to turn the compressor continuously.

Question 6

What type of duct is at the rear of the engine?

Answer 6

Convergent.

Question 7

How is potential energy defined?

Answer 7

Energy at rest or stored energy.

Question 8

What is the equation for potential energy?

Answer 8

PE= m x g x h

Question 9

How is kinetic energy defined ?

Answer 9

Energy in motion.

Question 10

What is the equation for kinetic energy?

Answer 10

KE= 1/2 x m x v^2

Question 11

What is Newton’s first law?

Answer 11

Law of inertia.

Question 12

What is Newtons 2nd law?

Answer 12

F=m x a

Question 13

What is newtons 3rd law?

Answer 13

Every action has an equal and opposite reaction.

Question 14

How does the Brayton cycle provide thrust?

Answer 14

By using air as a working fluid.

Question 15

Describe the volume and pressure of the Brayton cycle?

Answer 15

Variable volume, constant pressure.

Question 16

How is the air accelerated through the engine in the Brayton cycle?

Answer 16

Increasing pressure.

Adding heat energy.

Final conversion back to KE as high velocity jet efflux.

Question 17

What are the 4 stages of the Brayton cycle?

Answer 17

Intake, compression, combustion, exhaust.

Question 18

What happens at the inlet duct?

Answer 18

Pressure increases.

Question 19

What happens to pressure at the compressor?

Answer 19

It further increases.

Question 20

What happens to pressure at the combustion chamber?

Answer 20

Remains constant, volume increases.

Question 21

What happens to pressure at the turbine?

Answer 21

It decreases.

Question 22

What stages does isobaric heating occur?

Answer 22

2 to 3

Question 23

Where does isobaric heating take place ?

Answer 23

In the combustion chamber

Question 24

What is the hottest point in the engine?

Answer 24

The rear of the combustion chamber/ 1st stage of the nozzle guide vane.

Question 25

At what stages does isentropic compression occur?

Answer 25

1 to 2.

Question 26

At what stages does isentropic expansion occur?

Answer 26

3 to 5.

Question 27

What do the stationary vanes/ stators do?

Answer 27

They straighten and guide air onto the rotor blades.

Question 28

What happens in stage 4 to 5?

Answer 28

Remaining energy, on its discharge to the atmosphere, provides a propulsive jet in the nozzle.

Question 29

What is the process from 0 to 5 called?

Answer 29

Isobaric heat release.

Question 30

Where is the point with the highest static pressure?

Answer 30

The start of the combustion chamber.

Question 31

What is the equation and unit for Force?

Answer 31

F= m x a. Newtons.

Question 32

What is the equation and unit for Weight?

Answer 32

W= m x a. Newtons.

Question 33

What is the equation and unit for Work done?

Answer 33

W= F x d Joules.

Question 34

What is the equation and unit for power?

Answer 34

P= W/t Watt.

Question 35

What is the role of the turbine?

Answer 35

To supply power to turn the compressor.

Question 36

How is motion defined?

Answer 36

The continuous change of position of place.

Question 37

How is acceleration defined?

Answer 37

The rate of change of velocity.

Question 38

What is equation and unit for acceleration?

Answer 38

A= change in V/ t m/s^2.

Question 39

How is speed defined?

Answer 39

How far an object will travel in a specific time.

Question 40

How is velocity defined?

Answer 40

The rate of change of motion in a particular direction. Vector quantity.

Question 41

What was the first type of engine?

Answer 41

Piston type.

Question 42

What was the pro and con of the piston type engine and where was it used?

Answer 42

+ fuel efficient. - performance decreases at high altitudes. Only used on small aircraft.

Question 43

What are the 3 things an aircraft engine supplies.

Answer 43

Hydraulic power. Electric power. Bleed air.

Question 44

What are the 4 types of gas turbine engines in aircraft?

Answer 44

Turobojet, turbonfan, turboprop, turboshaft.

Question 45

What are the advantages of the turbojet engine?

Answer 45

+ relatively simple design + capable of very high speeds + takes up little space

Question 46

What are the disadvantages of the turbojet engine?

Answer 46

- high fuel consumption - loud - poor performance at slow speeds - limited in range and endurance

Question 47

Why is a convergent duct used?

Answer 47

To increase thrust.

Question 48

In a turbofan engine, what do the front fan set do?

Answer 48

They produce 80% of thrust from energy.

Question 49

What is a spool?

Answer 49

A turbine driving a compressor through a shaft.

Question 50

What does a twin spool engine consist of?

Answer 50

A high pressure turbine driving a high pressure compressor. A low pressure turbine driving a low pressure compressor and fan.

Question 51

Describe a 3 spool engine?

Answer 51

A high pressure turbine driving a high pressure compressor. An intermediate turbine driving an intermediate compressor. A low pressure turbine driving a fan.

Question 52

What are the advantages of a turbofan engine?

Answer 52

Fuel efficient. Quieter than turbojet. Streamlined.

Question 53

What are the disadvantages of a turbofan engine?

Answer 53

Heavier than turbojet. Large frontal area. Inefficient at very high altitudes.

Question 54

Describe the function of a turboprop engine?

Answer 54

To produce shaft horsepower to drive a propellor.

Question 55

What are the advantage of a turboprop engine?

Answer 55

Very fuel efficient.

Question 56

What are the disadvantages of a turboprop engine?

Answer 56

Limited forward airspeed. Gearing systems are heavy and can break down.

Question 57

What is the purpose of a turboshaft engine?

Answer 57

To produce shaft horsepower to drive machinery instead of thrust.

Question 58

What does a turboprop engine incorporate?

Answer 58

A compressor, combustion and turbine within a gas generator.

Question 59

How does a turboprop engine differ from a turbojet?

Answer 59

Additional turbines. Power shaft. A reduction gearbox. All to drive the propeller.

Question 60

What are the advantages of a turboshaft engine?

Answer 60

Higher power to weight ration than piston engine. Smaller than piston engine.

Question 61

What are the disadvantages of a turboshaft engine?

Answer 61

Loud. Complex gear system connected to shaft can break down.

Question 62

What are the disadvantages of a turboshaft engine?

Answer 62

Loud. Complex gear system connected to shaft can break down.

Question 63

Where is a turboshaft engine used?

Answer 63

APU and helicopters.

Question 64

What is the cold section of an engine?

Answer 64

From the inlet to the compressors/ diffusers.

Question 65

What is the hot section of an engine?

Answer 65

From the combustion chamber to the exhaust.

Question 66

What materials are engines made from?

Answer 66

Aluminium, ceramic, composite, cobalt, nickel, CRES, titanium.