PhD defense - Y. Colin

Numerical simulation of the distortion generated by crosswind inlet flows

Delivered by ENSAE Toulouse
Speciality: Fluid dynamics

December 13, 2007 - CERFACS

Nacelles design must fulfill geometrical constraints and engine requirements. One of the engine requirements is focused notably on the homogeneity of the flow in front of the fan which is quantified by the distortion levels of the total pressure in this plane. Airplane on the ground with crosswind is a critical case for the nacelle. Subsonic or supersonic separations occur in the inlet depending on the engine mass flowrate. The resulting heterogeneity of the flow may account for the outbreak of aerodynamic instabilities of the fan blades and, if the distortion is large enough, the fan might stall. The goal of this study is to have a robust, accurate and efficient tool capable of simulating complex flows around and inside a nacelle in a crosswind and to predict the distortion levels. This application is featured by the cohabitation of incompressible and transonic areas around the inlet lip. Local preconditioning procedures are used to compute low Mach regions with the compressible elsA software. The second flow feature of this application is the considerable hysteresis phenomenon occuring in the separation and reattachment processes, conditioning the time integration techniques. Lastly, an accurate description of complex three-dimensional separations requires the investigation of RANS turbulence models along with the study of transition phenomena. These models are developed and tested on two different nacelles presenting different geometrical features.

P. Sagaut	Professor - University Pierre et Marie Curie, Paris VI	President
T. Alziary de Roquefort	Professor - ENSMA-LEA, Poitiers	Referee
C. Hirsch	Professor - University of Bruxelles	Referee
N. Kroll	Numerical methods department leader - Institute of Aerodynamics and Flow Technology, DLR, Braunschweig	Member
P. Chanez	Research engineer - SNECMA, Villaroche	Member
J.F. Boussuge	Research engineer - CERFACS, Toulouse	Member
B. Aupoix	Senior researcher - ONERA, Toulouse	Advisor