02-01-2013, 11:53 AM
Aircraft Propulsion Systems
1Aircraft Propulsion.ppt (Size: 632.5 KB / Downloads: 129)
Analysis
Energy control volume per engine component
Pressure and temperature changes for ideal engine
With efficiency definitions: pressure and temperature changes for non-ideal engine
Control Volume over complete engine:
Momentum balance=> thrust, propulsion efficiency
Energy balance or thermo analysis:
Brayton cycle: Thermal efficiency
Thermodynamic cycles
Diagram that looks at the change of state variables at various stage of the engine
Ideal gas turbine: Brayton cycle
Isentropic compression, constant p heat addition, constant p heat rejection
First law of thermodynamics analysis gives expression for ηth
Definition of component efficiencies
Relates actual total temperature increase to an isentropic temperature increase
The isentropic temperature can be related to the total pressure using isentropic relations
The total pressure distribution is determined from front to back.
Each stage has an effiiciency like this.