来流侧分隔板对后视镜尾部流场影响的研究

Research on the influence of the incoming flow side partition plate on the flow field of the rearview mirror tail

后视镜作为汽车安全行驶的重要部件,研究其尾部流场结构对汽车减阻降噪具有重要意义。基于粒子图像测速技术(PIV),分别测量了一般类后视镜钝体与带有来流侧分隔板的类后视镜钝体的瞬时尾部流场,在此基础上,展开了流场的统计学分析。时均流场表明,在来流侧采用分隔板削弱了后视镜的旋涡脱落强度,推迟了尾部分离区的形成。采用功率谱密度分布以及利用本征正交分解(POD)的方法研究2种类后视镜模型的尾流结构,分析表明:带有分隔板的类后视镜模型旋涡脱落频率有所下降,其尾部流场处于相对稳定的状态;在分隔板作用下,POD前两阶模态的能量占比明显降低,模态的空间分布出现了小尺度的旋涡结构,这进一步证实了分隔板对旋涡脱落的抑制作用以及对后视镜减阻降噪的积极影响。

As an important part of automobile safety driving,it is of great significance to study the rear flow field structure of rearview mirror for automobile drag reduction and noise reduction.Based on particle image velocime-try(PIV),the instantaneous tail flow fields of the general rearview mirror blunt body and the rearview mirror blunt body with inflow side partition are measured.On this basis,the statistical analysis of the flow field was car-ried out.The time-average flow field shows that the vortex shedding strength of the rearview mirror is weakened,and the formation of the tail separation zone is delayed by using the separator on the inflow side.The power spec-tral density distribution and the proper orthogonal decomposition(POD)method are used to investigate the wake structure of the two rearview mirror models.The analysis shows that the vortex shedding frequency of the rearview mirror with a partition plate decreases,and the flow field in its tail is in a relatively stable state.Under the action of the partition plate,the energy ratio of the first two modes of POD is significantly reduced,and the spatial distri-bution of the modes shows a small-scale vortex structure,which further confirms that the splitter plate has an in-hibitory effect on vortex shedding and a positive effect on the drag and noise reduction of the rearview mirror.