Gas Turbine Compressor

Question 1

The less work the turbine has to do to drive the compressor, the more energy is
left to generate blank

Answer 1

Thrust

Question 2

Modern designs achieve up to X:1. compression ratio in an axial compressor

Answer 2

35:1

Question 3

Axial flow compressor; Air flows parallel to the blank

Answer 3

Axial flow compressor; Air flows parallel to the axis of the engine

Question 4

What happens to pressure in a divergent duct.

Answer 4

Increases.

Question 5

What happens to tempurature in a divergent duct.

Answer 5

Increases

Question 6

What happens to velocity in a divergent duct.

Answer 6

Increases

Question 7

What happens to velocity in a divergent duct in a centrifugal compressor?

Answer 7

Increases

Question 8

What happens to pressure in a centrifugal diffuser?

Answer 8

Increases

Question 9

What happens to tempurature in a centrifugal diffuser?

Answer 9

Increases

Question 10

What happens to velocity in a centrifugal diffuser?

Answer 10

Decreaser

Question 11

What compressor cannot aero dynamically stall?

Answer 11

Centrifugal

Question 12

Generally, a maximum compression ratio of X:1 per stage can be achieved in centrifugal compressor

Answer 12

4.5

Question 13

To achieve a greater mass flow the impeller can be blank: a double entry
impeller in a centrifugal compressor.

Answer 13

Double sided.

Question 14

To achieve a greater blank the impeller can be double-sided: a double entry
impeller in a centrifugal compressor

Answer 14

Mass flow

Question 15

All large commercial designs use blank compressor

Answer 15

Axial flow

Question 16

A rotor + a stator = blank

Answer 16

A stage

Question 17

Rotor adds blank to the airflow.

Answer 17

Energy

Question 18

The pressure rise across a single stage is usually only about blank%

Answer 18

10-20

Question 19

The partial breakdown of airflow through an engine is also known as what?

Answer 19

A stall

Question 20

a complete reversal of the airflow through the compressor is know as a what?

Answer 20

Deep surge

Question 21

Gas turbine engines have a very narrow operating band, limited by the air mass
flow and the overall pressure ratio. Beyond this operating band the compressor
becomes blank.

Answer 21

Unstable

Question 22

What happens to the pressure ratio at high rpms?

Answer 22

Increases

Question 23

What rpm would you have a higher margin of safety?

Answer 23

High

Question 24

A stall results in reduced blank through the compressor and thus reduced thrust

Answer 24

Air mass flow

Question 25

If fuel flow isn’t reduced the combustion temperature will quickly rise. The principal symptoms of compressor stall is a high blank

Answer 25

EGT

Question 26

In an extreme case flames may be seen exiting the intake: • This is blank and is often accompanied by a loud bang

Answer 26

Deep surge

Question 27

Over-fueling can cause a surge by creating excessive blank in the combustor: • Over-fueling surge has been mostly eliminated by modern electronic fuel control units.

Answer 27

Pressure

Question 28

What is a variable inlet guide vane used for?

Answer 28

Prevent stall/surge

Question 29

What is a variable inlet guide vane?

Answer 29

They change aoa to prevent stall

Question 30

Why are multiple stool compressors used?

Answer 30

To prevent stall

Question 31

(Handling bleeds) Inter-stage bleed valves vent pressure during the start to improve the axial flow across the blank

Answer 31

Compressor

Question 32

Generally, the valves are blank (under spring pressure) with the engine switched off and gradually close, to become fully blank at ground idle speed

Answer 32

Open - closed

Question 33

If a compressor stall occurs, quickly establish straight flight and blank the blank blank

Answer 33

Close the thrust leavers

Question 34

What would you find on a Lp compressor fan blade?

Answer 34

Snubber

Question 35

The tips of the stators are often joined by a blank to avoid energy losses and reduce vibration

Answer 35

Shorid

Question 36

What does a shroud do?

Answer 36

Reduce energy loss and vibration

Question 37

What spins the compressor?

Answer 37

Turbinw

Question 38

Is a centrifugal or axial compressor cheaper?

Answer 38

Centrifugal

Question 39

Does a centrifugal or axial compressor have a higher compression ratio?

Answer 39

Axial (35:1)

Question 40

Is a centrifugal or axial compressor more efficient?

Answer 40

Axial compressor

Question 41

At what P does the highest pressure occur?

Answer 41

P3

Question 42

The Compressor will deliver high pressure (compressed) air into the mid-frame diffuser (Px)

Answer 42

P3

Question 43

The diffuser also allows a separation of airflow into dilution air(cooling) (Xx%) and combustion air (keeps fire alight) (Xx%);

Answer 43

80% 20%

Question 44

What do you need to check is increasing when you press the engine anti ice?

Answer 44

EGT

Question 45

Bleed Air is taken from several compressor stages to be used for various internal engine tasks and externally to supply hot or high pressure air to aircraft systems • But this blanks mass flow and increases temperature, hence: • blanks power thrust • blanks specific fuel consumption

Answer 45

Reduces mass flow reduces thrust increases fuel consumption

Question 46

X pressure air is used to ‘cool’ the turbine nozzle guide vanes, the turbine blades and the turbine discs XP air is used to cool the accessories

Answer 46

High - low