Turbine Engine Part 1

Question 1

Bypass ratio =

Answer 1

Bypass air flow / compressor(core) mass flow

Question 2

Bypass air mass flow =

Answer 2

bypass air mass flow - compressor(core) air mass flow

Question 3

Inlet air mass flow =

Answer 3

bypass air mass flow + compressor(core) air mass flow

Question 4

compressor(core) mass flow =

Answer 4

inlet air mass flow - bypass air mass flow

Question 5

A spool is:

A ____ of __________ stages with a shaft driven by one or more ______.

Answer 5

A group of compressor stages with a shaft driven by one or more turbines.

Question 6

Centrifugal compressor:

The outflow of air is -

Answer 6

radial

Question 7

A stage is:

One set of ____ and one set of _____ blades

Answer 7

One set of rotor and one set of stator blades

Question 8

Compressor surge is accompanied by a -

Answer 8

load bang, loss of power, vibration and an increase in EGT.

Question 9

Choke stall:

The choke stall occurs when the airflow -

And occurs at -

Answer 9

is too high in relation to RPM

low angles of attack

Question 10

The stall:

The stall occurs with -

or -

And occurs at -

Answer 10

high RPM in relation to normal airflow

low air velocity in relation to normal rpm.

High angles of attack

Question 11

In relation to temperature:

The reduction of flow, that can lead to a compressor stall, can be caused by -

Answer 11

high inlet temperatures

Question 12

The following general methods are used to avoid this type of stall(Normal stall):

1. Use of _______ angles of attack in front stages(derating) to avoid ________ angles of attack under conditions of ______ engine RPM.
2. Introduction of ____ _____ in the middle or rear of the compressor allows some of the air to escape which _______ the airflow in front of the compressor at low engine speeds.
3. Use of two-speed rotors so that the front RPM ______ more than the ____ at low engine speeds so that the choked airflow from the rear is equalled by the low flow from the front
4. Use of ______ guide vanes and stator vanes in the ____ stages of the compressor so that the angle of attack can be controlled at low rpm.
5. Use of a _______ area exhaust nozzle to unload the compressor during acceleration

Answer 12

.
.
.
1. Use of reduced angles of attack in front stages(derating) to avoid excessive angles of attack under conditions of reduced engine RPM.

2. Introduction of bleed valves in the middle or rear of the compressor allows some of the air to escape which increase the airflow in front of the compressor at low engine speeds.
3. Use of two-speed rotors so that the front RPM reduce more than the rear at low engine speeds so that the choked airflow from the rear is equalled by the low flow from the front
4. Use of variable guide vanes and stator vanes in the early stages of the compressor so that the angle of attack can be controlled at low rpm.
5. Use of a variable area exhaust nozzle to unload the compressor during acceleration

Question 13

Controlled acceleration can avoid -

Answer 13

rapid acceleration stall when slamming the thrust lever

Question 14

Excessive inlet temperatures can be caused by?

Answer 14

Ram air rise

Question 15

Compressor stall:

Mild stalls can be identified by rapid -

RPM -

EPR -

Answer 15

turbine temperature increase or fluctuation

fluctuation

decrease or fluctuation

Question 16

Compressor stall:

Severe stalls can cause loud -

Answer 16

bangs, flame, vapour or smoke.

Question 17

The opening of the start lever provides fuel and ignition. During start, the start level should not be opened before -

Answer 17

15% N2 and normally not opened until 20% N2

Question 18

During start, the turbine self sustaining speed is at -

Answer 18

30% N2