The Gas Turbine Engine Part 1

Question 1

Four cycles of a gas turbine engine:

Answer 1

Induction

Compression

Combustion

Expansion

Question 2

Thrust of a turbine can be calculated:

Answer 2

Thrust (t) = Ms (V2 - V1) / g

T = thrust in pounds

Ms = Mass flow per second

V1 = Inlet velocity

V2 = Jet velocity

g = gravitational acceleration

Question 3

The four types of jet engines:

Answer 3

Turbojet
Turboprop
Turbofan
Turboshaft

Question 4

The three types of compressors?

Answer 4

Centrifugal flow
Axial flow
Centrifugal-axil flow

Question 5

The centrifugal flow compressor achieves compression of air by -

Answer 5

Accelerating it at right angles to the centre line of the engine

Question 6

The axial flow compressor accelerates the flow along the -

Answer 6

centreline of the engine

Question 7

The centrifugal-axial compressor -

Answer 7

combines the two effects

Question 8

A spool is defined as -

Answer 8

a group of compression stages

Question 9

What does this definition refer to:

The ability of the duct to convert kinetic energy at the duct inlet to static pressure energy at the compressor inlet without any loss in total pressure.

Answer 9

Duct pressure efficiency ratio

Question 10

What does this definition refer to:

This is defined as the aircraft speed at which the ram rise pressure is equal to the frictional pressure losses.

Answer 10

Ram Recovery Point

Question 11

The amount of air passing through the engine depends upon

Answer 11

1. The compressor RPM
2. Speed of the aircraft
3. Density of the air

Question 12

In a twin spool engine, the low pressure compressor is where the air -

Answer 12

enters the engine

Question 13

In a twin spool engine, the high pressure compressor is located -

Answer 13

behind the low pressure compressor

Question 14

The RPM of the low pressure compressor is entitled -

Answer 14

N1

Question 15

The RPM of the high pressure compressor is entitled -

Answer 15

N2

Question 16

Which negative effect:

This may be caused when the pressure demanded by the engine is greater than that which can be provided by the compressor blades. This results in an instantaneous breakdown of the airflow through the engine and the high pressure air in the combustion system is discharged forward through the compressor.

Answer 16

Compressor surge

Question 17

A choke stall will occur when?

Answer 17

the reduction of RPM reduces the compression ratio; this reduced pressure results in a larger volume of air in the rear of the compressor which tends to choke the engine

Question 18

factors that will increase the compressor blade angle of attack?

Answer 18

decreasing airflow velocity or increasing the RPM

Question 19

if a compressor stall is suspected immediate action must be taken to clear it. This will include -

Answer 19

reducing the pressure in the combustion chamber by reducing the power setting, which will reduce the flow of fuel, and at the same time increasing the forward speed of the aircraft by pitching down.

Question 20

Combustion chambers contain the following 5 basic elements:

Answer 20

1. A casing
2. Perforated inner linings
3. A fuel ignition system
4. Igniters
5. An excess fuel drainage system

Question 21

The reduction in velocity is achieved by the -

and the area where the burning takes place is called -

Answer 21

divergent diffuser shape of the forward part of the combustion chamber

The primary zone

Question 22

The swirl vanes and flare disc serves what purpose?

Answer 22

To further reduce the velocity of air entering the combustion chamber

Question 23

The percentage amount of airflow that is taken from main flow of air, by the swirl and flare disc leading to the primary zone??

Answer 23

20%

Question 24

The amount of airflow taken from the main flow, that passes through the secondary air holes to the primary zone?

Answer 24

20%

Question 25

The amount of airflow taken from the main flow, that passes around the primary zone entering the dilution air holes to cool burnt gases to a temperature acceptable to the turbine blades?

Answer 25

60%

Question 26

Which type of combustion chamber:

In this type of arrangement the cans are arranged in a circle around the centreline of the engine area and usually individually removable which makes inspection and maintenance easier.

They take a lot of space and increase the frontal area.

Answer 26

Multiple combustion chamber

Question 27

Which type of combustion chamber:

This chamber is essentially a single one formed from two concentric cylinders located around the centreline of the engine between the compressor outlet and the turbine. It is particularly suited to the axial flow engine where it makes the best use of available space and has low pressure loss. Theoretically, it is the most efficient burner chamber because, being a single large combustion chamber, the combustion process is achieved more evenly within the flame tube.

Answer 27

The annular combustion chamber

Question 28

Which type of combustion chamber:
This appears similar at first glance to the multiple combustion chamber system. The significant difference is that instead of each flame tube having its own air casing, one common air casing encloses a number of flame tubes.

Answer 28

The can-annular or tubo annular

Question 29

Which compressor type contains the following:

Compressor casing, or manifold, containing fixed air inlet guide vanes and outlet ports

The impeller

The diffuser(not the same as the same as the combustion chamber diffuser)

Answer 29

Centrifugal flow compressor

Question 30

Which compressor type contains the following:

The compressor consists of an annular passage through which the air passes and across which are arranged a series of small blades of aerofoil section, alternately fixed to the outer casing or rotating on a central shaft assembly

One set of rotor and one set of stator blades constitute one stage of compression

Answer 30

The axial flow compressor

Question 31

The compressor serves to?

Answer 31

The compressor squeezes the air that enters it into progressively smaller areas, resulting in an increase in the air pressure