Chp1 Introduction Flashcards
Why must heat be added to working fluid between compressor and turbine?
So that the turbine can produce added work
What are the three biggest effects on turbine efficiency?
“1) Compressor ratio
2) Turbine inlet temperature
3) Component efficiencies”
Out of these three, which has the biggest effect?
Compressor ratio
Where would you add an intercooler and why?
In between compressors to reduce compressor work
Where would you add a reheater and why?
In between turbines, to increase turbine work
What’s the difference between single shaft and twin shaft?
Single shaft good for fixed rotational speed (i.e. generators), twin shaft good for variable speed (i.e. planes or ships)
Why are reheaters and intercoolers effective?
Work required is directly proportional to inlet temperature.
One characteristic of multi-spool?
Mechanically independent but aerodynamically related
What is a turbojet?
Turbine powers just compressor; rest of gas is nozzle’d into a propulsion jet
What is a turboprop?
Secondary turbine powers propeller; mix of exhaust gas and propeller
What is a turbofan?
Mix of turbojet and turboprop; LP compressor bypasses some air into annular flow
When is a turboprop effective?
Lower speed aircraft
When is a turbojet effective?
Not so much anymore; superseded by turbofan
When is a turbofan effective?
High subsonic speeds; low noise
What are three reasons aircraft and industrial gas turbines are so different?
“1) Industrial expected 50 000 hours
2) Size and weight important for aircraft
3) Kinetic energy important for aircraft”
