Turbine Theory/Construction Flashcards
Four forces of flight:
Lift,
Gravity,
Thrust,
Drag.
Newton’s 1st law:
An object at rest will remain at rest, and an object in motion will continue in motion in a straight line and will not change its velocity unless it is acted upon by an outside force.
Newton’s 2nd law:
The amount an object will accelerate is inversely related to its mass and directly related to the amount of force acting on it.
Newton’s 3rd law:
For every action there is an opposite and equal reaction.
Bernoulli’s principle:
Any increase in the velocity of a moving fluid will result in a corresponding decrease in its pressure.
A specially shaped restrictor in a tube designed to speed up the flow of fluid passing through it.
Venturi
Turbine engines are rated in _____
Shaft horsepower.
A duct that has a decreasing cross section in the direction of the flow.
Convergent duct.
A duct that has an increased cross-sectional area in the direction of the flow.
Divergent duct.
T/F
As pressure increases, temperatures decrease.
False
Temperature follows pressure.
Subsonic air is ________. Compressible/Incompressible
Incompressible
Supersonic air is _______. Compressible/Incompressible
Compressible.
Rather than compressing in a venturi, subsonic air ______.
Speeds up.
Three types of pressure commonly used in gas turbine engine technology:
Absolute pressure,
Gage pressure,
Differential pressure.
Absolute pressure is referenced from ______.
Zero pressure.
Gage pressure is referenced from ______.
Existing atmospheric pressure.
Differential pressure is ______.
The difference between two pressures.
The ICAO standard day atmospheric pressure is _____.
29.92 in. Hg
(Inches of mercury)
14.7 psi
The ICAO standard day temperature is _______.
59 degrees F
15 degrees C
4 types of jet propulsion engines:
1) Rocket (non-air breathing)
2) Pulse-jet
3) Ram-jet
4) Gas turbine
4 types of gas turbine engines:
1) Turbojet
2) Turboprop
3) Turbofan
4) Turboshaft
6 steps of air in a turbojet engine:
1) Air is drawn in.
2) Air is compressed.
3) Air is diffused.
4) Air combustion.
5) Air flows over turbines.
6) Air is exhausted.
T/F
A turbofan engine is less efficient than a turbojet of comparable size.
False.
T/F
As air velocity decreases, pressure increases.
True.
A component of a gas turbine engine that decreases velocity and increases pressure of the air flowing through.
Diffuser.
Only ______ of the air is used in the combustion of a gas turbine engine.
25%
75% of the air taken into a gas turbine engine is used for _____ and ______.
Cooling.
Thrust.
The constant pressure cycle of energy transformation used by gas turbine engines is called the ________.
Brayton cycle.
Another name for a turbofan engine is ______.
Bypass engine.
The ratio of the mass of air moved by the fan to the mass of air moved by the core engine is the ________.
Bypass ratio.
A turbofan engine whose bypass ratio in less than 2:1 is a __________ engine.
Low bypass.
A high bypass turbofan engine has a bypass ratio of ______.
4:1 or greater.
2 types of turboprop engines:
1) Fixed shaft.
2) Free turbine.
Air pressure is highest in a gas turbine engine at what stage?
As it exits the compressor and enters the burner section.
Air in a gas turbine engine is at its highest temperature at what stage?
Between the combustors and the turbine.
Air in a gas turbine engine is at its highest velocity at what stage?
As it exits the turbine to be exhausted.
5 factors that affect thrust:
1) Airspeed.
2) Mass airflow.
3) Ram effect.
4) Water injection.
5) Afterburners.
3 major limitations of reciprocating engines:
1) Must use heavy parts to withstand movement of pistons.
2) Large number of moving parts requiring frequent overhauls.
3) Can only produce thrust by driving a propeller.
4 forces of motion:
1) Velocity
2) Acceleration
3) Momentum
4) Speed
2 types of energy:
1) Kinetic
2) Potential
