TurboJets Flashcards
What four types of Gas Turbine Engines are there?
Turbojet Engine
Turbofan Engine
Turboprop Engine
Turboshaft Engine (Helicopters)
People often confuse turbine engines with turbocharged engines. Why are they different?
Turbocharging is something that can only be done to a piston engine. It takes the exuast and reroutes it, then ompresses it, for additional power at high altitudes. It is something that is done to a piston engine.
A gas turbine engine is not piston powered
What is the one similarity that turbine engines have with piston engines?
There is a place for each of the ‘four strokes. Intake, Compression, combustion, Exhaust
Turbine Engines run very lean. What is the typical air to fuel ratio?
100 pounds of air to 2 pounds of fuel
Why do we have different types of Turbine engines?
What is the most basic type of turbine engine and how does it work?
The turbotjet is the most basic turbine engine.
Air is brought through the front, heated via combustion, then expelled out the back. Since the heated air exits at a higher velocity then its going in the front, thrust is created.
When are the terms ‘thrust’ and ‘torque’ used in relation to turbine engines?
Turbojets or jet engines use thrust
Turbo props use power or torque
Explain the stages of a turbojet engines function?
Large amounts of air are continuously brought into the engine through the intake or inlet (which come in many shapes and sizes)
The air then enters the compressor: a channel that steadily narrows and then forces the air through rows of airfoils. Each row produces a small jump in pressure. At this point the air will go through a difuser to enter the burner section.
The air then moves into the burner section where it is combined with a small amount of fuel and ignited.
After leaving the burner, the exhaust is then passed through the turbine. So instead of needing energy to turn the blades, the turbine uses the exhaust
Exhaust is then vented out the nozzel
What are the two types of compressors?
Axial Flow (has fins like things that get smaller and more numerous as you go along the compressor channel). Axial Flow compressors are efficient but require many ‘stages’). Can sometimes have two different compressors in one engine. A low pressure one and a high pressure one.
Centrifugal Flow typicalled found on the end of an axial flow compressor. Kind of spins around and flings the air out the sides
What three types of buners are there?
In a turbojet how does the turbine (at the end, after the burner stage) turn the compressor that feeds the burner stage?
It uses the exhaust epelled after the burner stage. Sort of a perpetual motion machine.
What are compressor sections called?
Spools.
