Turbine Test 2 Flashcards
Two sections of a turbine engine:
Cold section
Hot section
3 components of the cold section of a turbine engine:
Inlet
Compressor
Diffuser
3 components of the hot section of a turbine engine:
Combustors.
Turbine.
Exhaust.
N =
Compressor speed in RPM
N1=
Speed of LOW PRESSURE compressor.
N2=
Speed of HIGH PRESSURE compressor
N3=
Speed of the free turbine
P or psia =
Absolute pressure
T =
Abosolute temperature in Kelvin or Rankine
t =
Temperature in Fahrenheit or Celsius.
s (modifier) =
Static
t (modifier) =
Total or turbine
3 typical ducts for turboprop engines:
1) Ducted spinner inlet
2) Conical spinner inlet
3) Underscoop inlet
Most subsonic inlet ducts are what type?
Divergent.
To slow the air and convert its velocity into pressure.
Supersonic inlet ducts are what type?
Convergent-Divergent duct.
Used to create a shock wave to slow the supersonic air.
The _______ inlet has almost no duct losses and is used when calibrating gas turbine engines.
Bell mouth.
______ may be installed to prevent debris from being sucked into the engine of aircrafts while on the ground.
Vortex dissipaters.
3 types of compressors:
1) Centrifugal compressors.
2) Axial-Flow compressors.
3) Hybrid compressors.
3 typical parts of a centrifugal compressor:
1) Impeller
2) Diffuser
3) Manifold
Axial-Flow compressors use _____, _____ and _____ to move air and build pressure.
Inlet Guide Vanes.
Rotor Blades.
Stator Vanes.
T/F
A compressor’s rotor blades rotate to force air between the inlet guide vanes.
False.
Between the stator vanes
If the ______ becomes excessive, the air foils are subject to stalls.
Angle of attack.
The angle of attack of an air foil is the angle formed between its _____ and the _____.
Chord line.
Relative wind.
Angle of attack is determined by 2 factors:
1) Velocity of airflow.
2) Rotational speed of the compressor.
5 causes of compressor stall and surge:
1) Abrupt flight maneuvers.
2) Choking of engine airflow.
3) High crosswind.
4) Excessive pressure in burner section.
5) Obstruction to inlet airflow.
2 Types of axial-flow compressors:
1) Single spool.
2) Dual spool.
The first-stage compressor in a dual spool gas turbine engine:
Low-pressure compressor.
The second-stage compressor in a dual-spool gas turbine engine:
High pressure compressor.
The high pressure compressor is called the ______.
N2 Compressor.
The low pressure compressor is called the _______.
N1 compressor.
T/F
The N1 compressor is rotated by the starter.
False.
N2 compressor. (Due to its lighter weight.)
T/F
The N1 compressor is driven by the rearmost stages of the turbines.
True.
T/F
The speed of the N1 compressor is held steady by the governor in the fuel control.
False.
The N2 is governed while N1 changes its RPM according to atmospheric changes.
A gas turbine engine consisting of both centrifugal and axial-flow compressors:
Hybrid compressor engine.
_______ combustors make the most of limited space in axial-flow compressor engines.
Annular.
___________ combustors are used in engines where overall length is critical.
Reverse-flow annular.
2 types of turbines used in aircraft engines.
1) Axial.
2) Radial inflow.
What section operates in the most hostile environment of the engine?
Turbine section.
The turbine section consists of a ring of ______ and one or more stages of ______.
Inlet guide vanes.
Turbines.
Each stage of a turbine consists of a set of _____ followed by a _____.
Guide vanes.
Turbine.
Holes on the turbine blades are called _____.
Gill holes.
Holes on the turbine blades are for ______.
Transforation cooling
Or film cooling
3 types of turbine blades:
1) Reaction.
2) Impulse.
3) Reaction-impulse blade.
3 main causes of turbine failure:
1) Creep.
2) Metal fatigue.
3) Corrosion.
The deformation of a metal part that is continually exposed to high centrifugal loads at high temperatures is called _____.
Creep.
A process in which cool air is blown around the turbine case, shrinking the case to minimize turbine blade tip loss.
Active Clearance Control.
ACC
T-shaped turbine blades used to reduce vibration and minimize tip loss.
Shrouded turbine blades.
TIT =
Turbine inlet temperature
TOT =
Turbine outlet temperature
ITT =
Interstage turbine temperature.
TGT =
Turbine gas temperature
4 EGT readings:
1) TIT
2) ITT
3) TOT
4) TGT
4 accessories powered by gas turbine engines:
1) Fuel pumps.
2) Oil pumps.
3) Hydraulic pumps.
4 Air conditioning.
To produce more thrust with exhaust gases, the exhaust system components must _____ and _____the stream of gases.
Straighten and accelerate
4 exhaust system components:
1) Exhaust collector.
2) Exhaust cone.
3) Exhaust pipe.
4) Exhaust nozzel.
3 types of combustors:
1) Multiple can
2) Can-Annular
3) Annular
