文档介绍
| The recent successes achieved to reduce tire and engine noise have resulted in a higher contribution of the wind noise in the overall perception of noise by car passengers. Up to now, wind noise has been largely assessed by wind tunnel testing; however there is an increasing need for numerical methods in order to evaluate the design as early as possible. If direct noise computation (DNC) is not reachable for industrial applications, hybrid methods based on acoustical analogy or stochastic modelling have already demonstrated good aptitudes. Nonetheless, as a first step, an accurate CFD simulation must be performed. In this study, the flow-induced noise of an automotive rain gutter has been investigated for Reynolds numbers based on the rain gutter height between 20 000 and 130 000. As both rain gutter’s height and oncoming flow’s direction vary along the A-pillar, two configurations have been designed to investigate these effects separately. In addition, two different profile sections of rain gutter were tested. This paper mainly focuses on the computation of the structures of the flow and surface pressure level; the propagation of sound in far field will be addressed in a further publication. The topology of the flow was assessed using steady RANS computation. Unsteady SAS-SST and DES models have been used to compute surface pressure fluctuations. As the flow was stable for the conventional SAS-SST model,forcing terms were used to switch to unsteady mode. Experimental data will be presented and used to validate the results of the numerical simulations.汽车排水气动声学仿真 |
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机械设计
