A柱—后视镜区域仿生造型对气动降噪的影响研究

发布时间：2019-06-02 03:25

【摘要】：汽车高速行驶时产生的车外气动噪声会严重影响到车内驾驶员以及乘员的乘坐舒适性,因此,对于车外气动噪声的控制和降低成为了提高乘坐舒适性的重要途径。通过实验以及仿真分析发现,当气流流经汽车A柱—后视镜区域时产生了严重的分离和紊乱情况,因此,该区域是车外气动噪声的研究重点。目前,国内外在对车外后视镜或者A柱上的气动噪声已有一些研究,但对于整个A柱—后视镜区域的气动噪声研究还很少,尤其是在该区域的仿生降噪研究更是少之又少。因此,本课题就A柱—后视镜区域,结合仿生学原理,将仿生造型应用在该区域,采用CFD数值仿真方法,研究仿生造型对某SUV流场以及声场的影响机理。首先通过广泛阅读国内外汽车气动噪声的相关文献,对国内外在汽车气动噪声方面研究有了一定的了解和掌握,学习了研究汽车气动噪声的方法以及仿生学理论。然后对本课题所采用的CFD仿真方法进行验证。通过油流法实验获得该车型侧窗表面的流线图;通过压力系数实验,获得侧窗表面监测点的压力系数。然后建立该SUV车型的仿真模型以及模拟风洞模型,进行稳态以及瞬态的仿真计算,分析A柱-后视镜区域流场以及声场,并与风洞实验结果进行对比,从而验证CFD仿真方法的可靠性和准确性。结合国家自然科学基金项目(NO.51175214基于柔性仿生车外造型的汽车内部气动噪声分析与控制方法研究),采用仿生半球凸起以及凹坑结构,对某款SUV车型的A柱-后视镜区域进行仿生气动降噪研究。在SUV的A柱、后视镜以及A柱-后视镜区域分别建立仿生半球凸起和凹坑模型,对六种仿生模型分别进行数值仿真计算,选取了具有代表性的模型1进行流场和压力分析,通过对三个典型平面的流场进行分析,发现仿生模型对于A柱-后视镜区域的流场具有一定的改善效果,因此,可以预测这种仿生模型也将有利于该区域气动噪声的降低。通过对比仿生模型和原模型的侧窗监测点1/3倍频程声压级曲线以及总声压级,发现六种仿生模型都在一定程度上起到了降低侧窗声压级的效果。为了进一步探究具有最优降噪效果的仿生结构单元形态、分布位置以及尺寸大小,利用正交试验设计,通过极差分析法对结果进行了综合的分析和判断。最终得到各个因素对气动降噪的影响大小排序。根据每一因素对应的最大Ki值,从而得到最优的仿生降噪方案。因此,对于汽车A柱-后视镜区域,采用仿生凸起和凹坑造型,将有利于改善侧窗表面的流场和声场,起到控制车外气动噪声的作用。本课题的研究将对后续汽车仿生气动降噪提供一定的指导和借鉴。
[Abstract]:The outdoor pneumatic noise caused by high speed driving will seriously affect the ride comfort of drivers and occupants. Therefore, the control and reduction of outdoor pneumatic noise has become an important way to improve ride comfort. Through experiments and simulation analysis, it is found that when the airflow flows through the A-column rearview mirror area of the automobile, there is a serious separation and disorder, so this area is the focus of the research on the pneumatic noise outside the vehicle. At present, there have been some studies on the pneumatic noise on the external rearview mirror or A column at home and abroad, but the research on the pneumatic noise in the whole A column rearview mirror area is still very few, especially in this area, especially the bionic noise reduction research is very few. Therefore, in this paper, the bionic modeling is applied to the A column rearview mirror region and the bionic principle, and the influence mechanism of bionic modeling on a SUV flow field and sound field is studied by using CFD numerical simulation method. Firstly, through extensive reading of the relevant literature of automobile pneumatic noise at home and abroad, we have a certain understanding and mastery of the research on automobile pneumatic noise at home and abroad, and learn the method of studying automobile pneumatic noise and the bionic theory. Then the CFD simulation method used in this paper is verified. The flow diagram of the side window surface of the vehicle is obtained by the oil flow method, and the pressure coefficient of the monitoring point on the side window surface is obtained by the pressure coefficient experiment. Then the simulation model of the SUV model and the wind tunnel model are established, the steady-state and transient simulation calculations are carried out, the flow field and sound field in the A-column rearview mirror area are analyzed, and the results are compared with the wind tunnel experimental results. The reliability and accuracy of CFD simulation method are verified. Combined with the National Natural Science Foundation of China (NO.51175214 based on the analysis and control method of automobile internal pneumatic noise based on flexible bionic vehicle external modeling), the bionic hemispheric bulge and pit structure are adopted. The bionic pneumatic noise reduction of A column rearview mirror area of a SUV model is studied. The bionic hemispheric bulge and pit models are established in the A column, rearview mirror and A column rearview mirror region of SUV, respectively. The six bionic models are simulated and calculated, and the representative model 1 is selected for flow field and pressure analysis. Through the analysis of the flow field in three typical planes, it is found that the bionic model has a certain effect on improving the flow field in the A column-rearview mirror region. Therefore, it can be predicted that the bionic model will also be beneficial to the reduction of pneumatic noise in this region. By comparing the sound pressure level curve and the total sound pressure level of the side window monitoring point 1 / 3 between the bionic model and the original model, it is found that the six bionic models have the effect of reducing the sound pressure level of the side window to a certain extent. In order to further explore the shape, distribution position and size of bionic structural units with optimal noise reduction effect, the results are comprehensively analyzed and judged by orthogonal experimental design and extreme difference analysis method. Finally, the influence of each factor on pneumatic noise reduction is sorted. According to the maximum Ki value corresponding to each factor, the optimal bionic noise reduction scheme is obtained. Therefore, for the A-column rearview mirror area of automobile, the bionic protruding and pit modeling will be beneficial to improve the flow field and sound field on the surface of the side window, and play the role of controlling the pneumatic noise outside the vehicle. The research of this subject will provide some guidance and reference for the follow-up automobile bionic pneumatic noise reduction.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.8;U461.1

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