15.4 COMPRESSORS

Question 1

what are the 2 main components of a compressor

Answer 1

rotor, stator

Question 2

what are the 2 functions of the compressor

Answer 2

supply air to combustion chamber, supply bleed air

Question 3

whats the combination of a rotor and stator called

Answer 3

compressor stage

Question 4

whats the first part of the compressor stage

Answer 4

rotor

Question 5

if there are stator vanes infront of a compressor stage what are they called

Answer 5

inlet guide vanes

Question 6

what are the stator vanes in the fan duct called

Answer 6

outlet guide vanes

Question 7

what do outlet guide vanes do

Answer 7

improve airflow into fan nozzle

Question 8

what are the 2 compressors currently used in turbine engines

Answer 8

centrifugal flow compressor, axial flow compressor

Question 9

what is the pressure rise ratio in centrifugal compressors

Answer 9

8:1

Question 10

what does a centrifugal compressor consist of

Answer 10

impellar, diffuser

Question 11

where are axial flow compressors usually found

Answer 11

turbofans

Question 12

explain the axial flow compressors airflow

Answer 12

original direction but just compressed

Question 13

whats an advantage of centrifugal compressors

Answer 13

can work at higher rotational speeds

Question 14

what is a stage

Answer 14

rotor, stator pair

Question 15

on fan blades what 3 parameters affect the centrifugal forces

Answer 15

rotor speed, blade mass, distance of blade from centre of rotation

Question 16

on blades what numbers are written on them

Answer 16

part number, serial number, moment weight

Question 17

what is the moment weight the product of

Answer 17

blade mass, and distance from centre of gravity

Question 18

how do you replace a fan blade

Answer 18

with another blade which weight is as close to the old one as possible

Question 19

what one thing axial and centrifugal flow have in common

Answer 19

they are very sensitive to airflow changes

Question 20

the airflow into the rotor is smooth as long as

Answer 20

the angle of attack to the rotor blades is small

Question 21

if you increase rotor speed does angle of attack get bigger or smaller

Answer 21

bigger

Question 22

how does compressor stall occur

Answer 22

angle of attack increases while inlet air velocity decreases

Question 23

what is compressor surge

Answer 23

severe form of compressor stall

Question 24

what happens to airflow in compressor surge

Answer 24

reverses

Question 25

where can compressor surge occur

Answer 25

fwd or aft compressor stages

Question 26

what are some reasons for compressor stall or surge

Answer 26

dents, damaged parts, dirty blades, broken combustor components

Question 27

operational reasons for stall or surge

Answer 27

engine speed far below design speed, incorrect acceleration/deceleration

Question 28

what are methods to avoid stall and surge

Answer 28

compressor bleed valves, dual or triple spools, compressor stator vanes

Question 29

explain bleed valves in preventing stall or surge

Answer 29

open at low engine speed so excess air can leave

Question 30

explain variable inlet vanes in preventing stall or surge

Answer 30

optimum angle of attack for every engine speed

Question 31

what is the rough engine compressor ratio

Answer 31

1.3:1

Question 32

does the compressor pressure increase or decrease through each stage

Answer 32

increase slightly

Question 33

why are many stages needed in the compressor

Answer 33

to raise the pressure ready for efficient combustion

Question 34

an annular combustion chamber has design for small engines and APUs, whats this called

Answer 34

reverse flow combustion

Question 35

where and how many igniter plugs are on an engine

Answer 35

lower half, 2

Question 36

what does the dome do

Answer 36

connects inner and outer liner