Q02 Gas Turbines Compressors

Question 1

Inlet Guide Vanes IGVs are located where?

Select one:

a.Before the Fan.

b.After the fan and the first stage Rotor.

c.After the fan, but before the fan straightening vanes.

d.Just before the HP compressor first stage Rotor.

Answer 1

d.Just before the HP compressor first stage Rotor.

Question 2

The fan in a High Bypass Engine is on the same shaft as the;

Select one:

a.All the above

b.LP Turbine

c.Rearmost Turbine

d.HP Compressor

e.HP Turbine

Answer 2

b.LP Turbine
OR
c.Rearmost Turbine

Question 3

The air conditioning and pressurisation systems require air from the engine. Where is this air normally extracted from?

Answer 3

The Compressor

Question 4

A triple spool engine with an inlet air mass flow of 1800kg per second and an HP compressor mass flow of 200kg per second has a bypass ratio of;

Answer 4

8:1

The Cold Bypass is 1600 and the core is 200. 1600/200 is 8 making the ratio 8 to 1.

Question 5

What is the pressure ratio of one stage of a Centrifugal compressor?

Type your answer in the form X:1 where X is the number you wish to use.

Answer 5

4:1

Question 6

What are a compressor and its associated turbine called?

Answer 6

A spool

Question 7

Drag the Compressor Bleed Valves, Inlet Guide Vanes and Variable Stator Vanes to the correct locations.

Answer 7

IGV Inlet Guide Vane 1

VSV Variable Stator Vanes 2

Compressor Bleed Valves 3

Question 8

During start, the engine is accelerating, but slowly, and you feel vibration is high along with a steadily increasing EGT. What problem might you suspect?

Select one:

a.There is a deep surge

b.The compressor is stalling

c.The variable bleed valves on the compressor have opened too early.

d.The IGVs are opening instead of closing.

Answer 8

b.The compressor is stalling

Question 9

The compression ratio of a complete axial flow compressor can be?

Answer 9

35:1

Each stage raises the pressure by 10 to 20 percent. This is accumulative so pressure ratios of 35:1 are achievable.

Question 10

In a three-spool turbofan engine, what designator would the HP spool have when checking it’s speed?
Type in one of the following

1. N2
2. N1
3. N3
4. RPM
5. Torque
6. EGT

Answer 10

3. N3