基于 LES 方法的增升装置气动噪声特性分析

在气动噪声数值计算中，流场的求解精度对涡流扰动的细节计算以及声学的求解结果有着重要的影响。本文应用 LES 方法对增升装置的流场进行数值模拟，采用可穿透积分面的 Ffcows Wil1iams-Hawkings(FW-H)积分方法进行远场噪声计算。采用圆柱绕流算例对本文的数值计算方法进行了验证，验证结果表明：本文所使用的LES 方法能准确地捕捉到涡脱落、流动分离等非定常流动现象，可为远场气动噪声的计算提供精确的近场流动的数值解；基于 FW-H 的声类比方法能够精确高效求解远场气动噪声。在此基础上，对增升装置噪声产生的流动特性、远场特性、风速影响等进行了数值模拟研究。结果表明：缝翼产生气动噪声的主要原因是，流动在缝翼和主翼之间的凹槽形成的不稳定波以及缝翼钝后缘的小脱落涡；襟翼产生气动噪声的主要原因是，襟翼附近由于流动分离产生的高频的小尺度不稳定涡和低频的大尺度涡。

Analysis of aeroacoustics characteristics of high lift device using LES method

The accuracy of flow field has a significant impact on the details of vortex turbu-lence and aeroacoustic calculation results.LES method is used for high lift device flow field simu-lation,and Ffcows Williams-Hawkings integral surface is used for far-field noise calculation.In this paper,numerical results are validated comparing with test results of flow around cylinder, comparison shows that LES method used in this paper can capture unsteady flow like vortex shedding and detachment,and provide accurate near field flow solution for the following far field noise calculation,acoustic analogy based on FW-H equation can solve far-field noise accurately and efficiently.Based on this,the flow characteristics,far-field characteristics and flow speed in-fluence of high lift device noise generation are numerically studied in this paper.Results show that the slat noise is mainly caused by the unstable turbulence between slat and main element of high lift device and slat trailing edge vortex shedding;while the flap noise is mainly caused by small scale high frequency and large scale low frequency vortices generated around the flap.