扩散角对汽车风洞扩散段流动的影响

utomotive wind tunnel design is traditionally based on the experiences of existing wind tunnel designs and engineering correlations. Diffuser is a major component in the automotive wind tunnel, and its design is usually based on uniform incoming flow. In this paper, v2f turbulence model was used under two kinds of non-uniform incoming flow conditions to study the effects of different diffuser angles. The agreement of velocity distribution of model wind tunnel diffuser outlet between the CFD results and the test results indicates that v2f turbulence model can accurately capture the diffuser flow characteristics. Compared with uniform incoming flow, non-uniform incoming flow substantially increases total pressure loss by approximately 520%. Due to the competition between wall friction loss and flow separation loss, a minimum total pressure loss is found at certain diffuser angle. It is also found that the larger non-uniformity velocity of diffuser inlet, the larger the optimal diffuser angle.