gass turbin Flashcards
What is thrust force?
It is the product of the mass of the air times the acceleration given to it
how do you create Jet thrust?
Jet engine creates thrust by giving momentum to a mass of air or gas
What is propulsive force caused by
Solely the result of the ration to the mass of air existing the ballon
Is there “pushing effect” against the air?
No
There are 4 operations carried out on the air by an gas turbine
Compression, combustion, expansion and exhaust
All the 4 process occur continuously and at the same time
the brayton cycle
What is the difference between gas turbine piston engine?
combustion that creates the force
The amount of thrust produced depends on 2 factors
the mass of air that is accelerated and the acceleration given to it
What is the equation for the momentum thrust
Thrust = mass x velocity or T = MV
What is Compressor?
Air pressure increases steadily. The entire unit is contained within ta convergent duct to sustain velocity whilst pressure increases
What is diffuser?
a divergent duct between the compressor and composter. highest pressure here
What is combustion area?
continuous combustion at constant pressure
Are gas turbines constant pressure engine?
Yes
What is turbine?
Where energy is extracted from the gas stream. Causes a decrease in temperature, pressure and velocity
What is exhaust section?
in some designs pressure falls and velocity rises slightly
Propelling nozzle?
Velocity increases markedly at the propelling nozzle
What affects the thrust?
Altitude, speed, ambient temperature, engine bleed, intake heating
The maximum thrust is produced when…
the aircraft is stationary on the ground
What is Specific Fuel Consumption (SFC)
Ratio of fuel mass consumed to produce a init of thrust per unit per time
What is Thermal Efficienty?
Describes the efficiency with which fuel energy iOS converted to kinetic energy
- Gas turbine engines are about 30% thermal effineceit
What is propulsive efficiency
Kinetic energy os translated into propulsive force
What are the factors affecting SFC
Turboject engine, SFC is lowest
