The document provides an overview and goals for analyzing different types of gas turbine engines including turbojet, turbofan, and ramjet engines. It outlines the planned analysis of individual engine components including inlets, combustors, compressors, turbines, and control volume analysis. The analysis will use thermodynamic cycles and definitions of efficiency to evaluate performance parameters like propulsion efficiency, thermal efficiency, and thrust specific fuel consumption. Both ideal and non-ideal analyses are discussed for ramjet and turbojet engines.

1. Review AE430 Aircraft Propulsion Systems Gustaaf Jacobs

2. Note Bring Anderson to exam for tables.

3. Goals Understand and analyze gas turbine engines: Turbojet Turbofan (turbojet + fanned propeller)! Ramjet

4. Analysis 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

5. Analysis Detailed component analysis Inlets Subsonic flow analysis in 1D Pressure recovery estimate Shock analysis in 1D inlet (converging-diverging) Estimate of losses External deceleration principles 2D shock external deceleration Oblique shock analysis Estimate spillage and losses

6. Analysis Combustor Qualitative idea of combustion physics Fuel-air ratio (stoichiometric) Flame speed Flame holding Quantitative: pressure loss with 1D channel flow analysis + heat addition=> not treated due to time restrictions Compressor/Turbine Estimate of pressure, temperature recovery with momentum and energy balance Velocity triangles analysis: first order estimate of compressor aerodynamics

7. Control Volume Analysis: Basic Idea T

8. Engine Performance Parameters Propulsion efficiency, ratio thrust power to add kinetic energy Thermal efficiency, ratio added kinetic energy to total energy consumption Total efficiency Thrust Specific Fuel Consumption

9. 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 η th

10. Ideal Ramjet Analyze each stage using thermodynamic analysis with energy balance and isentropic relations to find: P, T, p 0 , T 0 v e , T/m a f

11. Ideal Ramjet p t,0 =p t,7 , p 0 =p 7 => M 0 =M 7 T 7 > T 0 since heat is added during combustion, so v 7 >v 0 => Thrust Fuel to air ratio, use first law:

12. Non-isentropic compression and expansion: losses lead to lowered total pressure and temperature Define total pressure ratios before and after components to quantify the efficiency: r c , r n ,r d Non-ideal ramjet

13. Major difference with ramjet p total is not constant like in ramjet but increases and decrease in compressor and turbine. To find these ratios work from front to back through each stage Specific: compressor and turbine power are the same so (first law) Non-Ideal turbojet

14. Definition of component efficiencies E.g. diffuser 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.

15. Turbofan Example on blackboard.

16. Detailed analysis of components

17. Intakes Convert kinetic energy to pressure Subsonic External acceleration or decelleration depends on intake design and speed of aircraft High speed: spillage. Low speed: stall. Diffuser design: prevent stall: use computational (XFOIL, MSES) and experimental validation to design

18. Supersonic intake 1D: converging-diverging nozzle Ideal: isentropic decelleration supersonic to throat, subsonic after throat Not possible in practice Shocks in nozzle Possible design: shock close to throat and M~1 at throat Need overspeeding to swallow shock in throat. Kantrowitz-Donaldson: design condition is shock swallowing condition.

19. Supersonic diffuser 2-D nozzle Use multiple oblique shocks to slow flow down with small losses in total pressure Use oblique shock analysis

20. Combustor + Compressor Discussed in last classes