Test 2 Review

Question 1

Whats happening to the air in the diffuser?

Answer 1

Increase pressure

Stagnate Velocity

Question 2

How do we turn potential energy, into KINETIC energy?

Answer 2

Fuel + Ignition into the air mixture

Question 3

Where is the largest amount of kinetic energy found?

Answer 3

The OUTLET of the COMBUSTION chamber (Acceleration)

Question 4

What makes up the single stage of a compressor?

Answer 4

Inlet guide vane
Rotor
Stator

Question 5

What do we call the last stage stators, and what do they do?

Answer 5

Exit Guide Vanes

STRAIGHTEN airflow going into diffuser

Question 6

Function of a compressor STATOR?

Answer 6

Increase pressure, decrease velocity

due to its DIVERGENT shape

Question 7

What do we want CONSTANT in the COMPRESSOR? How do we get it?

Answer 7

Constant VELOCITY

We get it by the CONVERGENT shape from inlet to end (blades get SMALLER)

Question 8

What is it called when the blade AOA exceeds the critical AOA, caused by an IMBALANCE between the INLET and ROTATIONAL velocities

Answer 8

COMPRESSOR STALL

Question 9

What can happen if we leave a stall unchecked?

Answer 9

hung stall/SURGE = damage

Question 10

What is a compressor surge?

Answer 10

huge build of of PRESSURE released quickly through the front and back of engine

Question 11

When the aircraft is flying, what are the ways STALL/SURGE can occur?

Answer 11

airflow DISRUPTED/TURBULENT to engine

RAPID engine acceleration/deceleration

Question 12

If you’re in a high power setting and you feel a stall coming, what should you do?

Answer 12

Decrease power
IGV
Control Bleed Valves
Variable stators

Question 13

How do we fix a dirty engine?

Answer 13

Compressor wash (fluid/grit blast)

Question 14

Turbo prop and turbo shaft use what type of compressor?

Answer 14

Centrifugal

Question 15

Control bleed, what are do we get it from?

Answer 15

Mid section of Comp and diffuser

Question 16

What areas do we target with compressor bleed air?

Answer 16

Starting engine
Cabin Pressurization 
Cooling/Heating 
Engine Cooling 
Pressurization of reservoir 
Pumps  
ANTI ICE

Question 17

What do we use ram air for?

Answer 17

Engine Gen. Cooling

Question 18

Why do compressor blades have a twist?

Answer 18

for EVEN acceleration of air across the blades

Question 19

What are the types of blade root designs?

Answer 19

Dovetail
Fir Tree
Bulb root

Question 20

What are the purpose of blade root designs?

Answer 20

Radial movement (centrifugally)

Question 21

How do we protect from axial movement?

Answer 21

rivet
lock wire
lock tab

Question 22

What are the disadvantages of Axial Flow Compressors?

Answer 22

high cost
complex
high weight

Question 23

What are the disadvantage of a Centrifugal Compressor?

Answer 23

heavy

LIMITED compression ratio

Question 24

Compressor blades and discs are manufactured as a single assembly called what?

Answer 24

BLISK (blade integrated disk)

Question 25

Differential pressure between the rotors and stators caused by the camber of the blades is called what?

Answer 25

Cascading Effect

Question 26

What is cascade effect?

Answer 26

The process of involving velocity and pressure changes through several stages of compression

Question 27

When replacing the fan blade, what do you do?

Answer 27

Replace the one 180 degrees across it

Question 28

First stage of compressor stator are called what?

Answer 28

IGV

Question 29

What is the purpose of BLADE PROFILING?

Answer 29

reduce THICKNESS towards the the TIP to reduce VIBRATION (nat. frreq.)

Question 30

Purpose of the DILUTION HOLES?

Answer 30

Cools the flames before the nozzle guide vanes and turbines

Question 31

What to Ceramic Matrix Composites do? (CMC)

Answer 31

Increases thermal efficiency = increase propulsion efficiency

Question 32

What are the 2 functions of PRE SWIRL VANES?

Answer 32

1. Reduce Velocity | 2. Swirl fuel spray for better atomization = efficiency

Question 33

What provides a path to spread the combustion evenly for a MULTI Can Combustor?

Answer 33

Flame propagation tube

Question 34

What are the 3 different type of Combustion chambers?

Answer 34

Annular Can-Annular Multi Can

Question 35

What type of airc. do we use a Reverse Flow Annular?

Answer 35

PT6 engine Helicopter Turboprop

Question 36

What type of TURBINE for centrifugal flow compressor?

Answer 36

Radial Inflow

Question 37

What are the 2 types of TURBINES?

Answer 37

Radial Inflow | Axial Flow

Question 38

What is the purpose of the gas turbine?

Answer 38

Drive the compressor Gearbox Accessories

Question 39

What are the 2 designs of TURBINE STATORS?

Answer 39

1. direct air at ANGLE to TURN turbine ROTOR | 2. increase velocity (CONVERGENT STATORS ONLY)

Question 40

Where do we find convergent stators?

Answer 40

TURBINES

Question 41

What are the types of Turbine Blades?

Answer 41

Impulse Reaction Impulse-Reaction

Question 42

Impulse is?

Answer 42

Convergent stators

Question 43

Reaction is?

Answer 43

Straight through stators

Question 44

Is density DIRECTLY proportional to thrust?

Answer 44

Yes

Question 45

What will the gas turbine do on a turboshaft/turbo prop engine?

Answer 45

drive the compressor accessory gearbox

Question 46

What is the reduction gearbox driven by?

Answer 46

free turbine

Question 47

Engine airflow stations

Answer 47

Tt, Pt, Ps

Question 48

Purpose Vortex generators

Answer 48

smoothen airflow going into compressors

Question 49

Advantage of modular engine design?

Answer 49

Reduced maintenance cost

Question 50

Purpose of the holes in turbine stator/ rotor blades?

Answer 50

Convection/film cooling