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Joint Optimization of Aerodynamics and Aeroacoustics of Side View Mirrors

Mattias Stridh
Göteborg : Chalmers tekniska högskola, 2018. Examensarbete - Institutionen för mekanik och maritima vetenskaper; 2018:32, 2018.
[Examensarbete på avancerad nivå]

This thesis is carried out at China Euro Vehicle Technology (CEVT) and aims at developing a method for performing multidisciplinary optimization for automotive applications. Such applications could be to optimize side mirrors, a-pillars, spoilers etc. for disciplines such as aerodynamics, aeroacoustics, contamination etc. For this thesis the optimization is performed in terms of aerodynamics and aeroacoustics on the side view mirrors of a passenger car. Another part of the thesis is to investigate the possibilities to post process and analyse the results, in order to find and understand the design parameters and how they affect the different disciplines. Two design parameters are used in the study. One parameter is the position of the mirror along the car and the other is the angle between the side of the car and the inside of the mirror. The optimization procedure follows four steps. The geometry is first morphed in the pre processing program ANSA into the design that will be simulated. A surface mesh is saved as a geometry representation. The second step is that the surface mesh is loaded into FLUENT meshing which creates the simulation domain and the volume mesh. Step two is performed in two separate session simultaneously, one for the aerodynamic and one for the aeroacoustic simulations. The next step is that the volume mesh is read by FLUENT which simulates the flow and calculates the optimization parameters, drag for the aerodynamic simulations and sound pressure level for the aeroacoustic simulations. The final step is that the optimization program HEEDS determines the new morphing parameters to send to ANSA based on the results from the previous simulations. A bash script was written which reads the design parameters from a separate file and runs ANSA and FLUENT in the correct order. HEEDS changes the design parameters in this separate file and then runs the bash script to obtain the output variables. After the output is obtained the process starts over. It was found that the angle of the inside of the mirror should be increased slightly to reduce drag and SPL. The optimal choice of the x-position seemed to be outside of the investigated interval, moving the mirror as far back on the car as possible was best in terms of drag. The effect the x-position had on the noise on the side window was very small.

Nyckelord: Aeroacoustics, Aerodynamics, CFD, DES, Drag, MDO, SPL

Publikationen registrerades 2018-06-26. Den ändrades senast 2018-06-29

CPL ID: 255222

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