Aeroacoustic study on the roofbar of a truck using CFD

Examensarbete för masterexamen

Please use this identifier to cite or link to this item: https://hdl.handle.net/20.500.12380/185377
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Type: Examensarbete för masterexamen
Master Thesis
Title: Aeroacoustic study on the roofbar of a truck using CFD
Authors: Johansson, Erik
Abstract: Aeroacoustic CFD-simulations around a roofbar on a Volvo FH-series truck were performed with the purpose to find a method of how to perform an aeroacoustic simulation. The simulations included incompressible approaches using Detached Eddy Simulation (DES) with the SST k-! turbulence-model and Spalart-Allmaras turbulence-model as RANS-models, and Large Eddy Simulation (LES) but also a compressible approach using SST-DES. Turbulence models and compressibility effects were the main scopes of the project. The domain that was used proved to be unsuitable for both the compressible and the incompressible approach. The compressible case suffered from severe unphysical phenomena and the incompressible approach which removed the phenomena seemed to be too affected by stiff boundary conditions. Widening the domain could have mitigated the effects. The incompressible DES-cases proved to predict the ow separation point on the roofbar completely different compared to the incompressible LES. Also, turbulent scales could not be entirely developed downstream of the roofbar for the incompressible DES-cases which had a large impact on the acoustic surface sources for these cases. Presumably, the LES separation point could be explained by high turbulent viscosity. The behavior of the separation point cannot be unambiguously explained since measurements have not been done. It is therefore not clear which one of DES or LES that gave the best results, however, future recommendations are based on LES as the reference case. Among the realistic results only broadbanded noise sources were found. There were no major differences between SA-DES and SST-DES, however SSTDES showed somewhat closer results to LES and is therefore recommended to be used although it took relatively longer time to perform.
Keywords: Transport;Grundläggande vetenskaper;Akustik;Hållbar utveckling;Strömningsmekanik;Transport;Basic Sciences;Acoustics;Sustainable Development;Fluid mechanics
Issue Date: 2013
Publisher: Chalmers tekniska högskola / Institutionen för tillämpad mekanik
Chalmers University of Technology / Department of Applied Mechanics
Series/Report no.: Diploma work - Department of Materials and Manufacturing Technology, Chalmers University of Technology : 2013:66
URI: https://hdl.handle.net/20.500.12380/185377
Collection:Examensarbeten för masterexamen // Master Theses



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