LEARNING OUTCOMES

The objective of the course is to provide students with tools for the design of the different components of an aircraft engine: engine inlet, compressor, combustor, turbine, diffuser and nozzle.

AIMS AND LEARNING OUTCOMES

At the end of the course the student should be able to:

- perform an accurate cycle analysis of the aeroengine, identifying the boundary conditions for the design of the different components;

 - design, through a preliminary procedure, each aeroengine component: intake, compressor, combustion chamber, turbine and propulsive nozzle;

- analyze in detail the aerodynamics of each component;

- apply the matching of the components in order to identify the nominal operating point of the system.

TEACHING METHODS

Frontal lessons will be mainly employed in the course. The basic design rules of each component will be provided. Experimental and numerical results characterizing the real operation of each component will be also shown. It is strongly suggested the participation of the student to the lessons, since the examination is driven by arguments discussed and presented during the lessons 

SYLLABUS/CONTENT

• Performance of the engine. Analysis of the thermodynamic cycle of a turbojet engine. Pressure and temperature ratios of the cycle. Thrust and specific fuel consumption
• Layout of a turbojet engine. Definition of the main design parameters of the different engine  components.
• Engine inlet, compressor rig, combustor chamber, turbine, diffusers and nozzle, post-combustor. Analysis of the thrust characterizing the different components.
• Dimensioning and design criteria of the engine components:

1. Reduced mass flow for the dimensioning of the engine inlet. Diffuser performance chart from Sovran and Klomp. Effect of flow non uniformity on the pressure recovery and total pressure losses.
2. Design of the exit nozzle. Loss of thrust due blockage mass flow (discharge coefficient) and total pressure losses (due to boundary layer evolution). Comparison between converging and converging-diverging nozzles.
3.  Mean line design of compressors and turbines stages. Identification of the stage number. Radial equilibrium equation for the dimensioning of both compressor and turbine stages. Lieblein and Zweifel correlations for limitation of the aerodynamic loading of compressor and turbine blades, respectively. Design of compressor blades with NACA65 profiles. Design of parabolic-arc turbine profiles. Introduction to secondary flows evolution and their effects on total pressure and exit flow angle. Correlations.
4. Design of S-shaped duct. Effects of curvature radii and inlet flow unsteadiness.

• Kerrebrock and Lefebvre correlations for the determination of the total pressure losses within the combustor chamber.
• Matching of the different engine components. Off-design functioning of the engine. 

RECOMMENDED READING/BIBLIOGRAPHY

• S. Farokhi, “Aircraft Propulsion”, Wiley and Sons, 2009
• J. Mattingly, W. Heiser, D. Pratt, “Aircraft Engine Design: Second Edition”, AIAA Education Series 2002