远场假设对喷流噪声预测中格林函数求解的影响

发布时间：2018-03-27 19:05

本文选题：气动声学　切入点：剪切流　出处：《航空学报》2016年09期

【摘要】：目前基于雷诺平均Navier-Stokes(RANS)的喷流噪声预测方法在格林函数求解时,为简化求解过程,通常对喷流流动做平行流假设,对观测点做远场假设。随着格林函数求解方法发展,近年来的研究表明平行流假设对下游观测点格林函数的计算会引起较大偏差,而目前远场假设对格林函数求解的影响仍不清楚。为研究远场假设对喷流格林函数求解的影响,以二维喷流为例,采用计算气动声学方法(CAA)分别数值求解了观测点远场假设条件与实际条件下90°~150°方向喷流内伴随格林函数,进而分析远场假设对格林函数求解的影响。研究结果表明,对于不同方向的观测点,由观测远场假设导致的伴随格林函数求解偏差不尽相同,且对于越靠近喷流中心线方向的观测点,远场假设导致的偏差越大,其中150°方向观测点,采用远场假设后,格林函数计算结果最大偏差达到-15dB以上。因此,对于靠近喷流中心线方向的噪声观测点而言,为避免预测偏差,应采用实际观测条件求解喷流格林函数。
[Abstract]:At present, in order to simplify the solution process of jet noise prediction method based on Renault average Navier-Stokes Stokes RANSs, in order to simplify the solution process, we usually make parallel flow hypothesis for jet flow and far-field assumption for observation point. Recent studies have shown that the parallel flow hypothesis will cause a large deviation in the calculation of the Green's function at the downstream observation point, but the effect of the far-field hypothesis on the solution of the Green's function is still unclear. In order to study the effect of the far-field hypothesis on the solution of the jet Green's function, Taking the two-dimensional jet flow as an example, the numerical solution of the adjoint Green's function in the 90 掳~ 150 掳direction jet is obtained by using the computational aero-acoustics method (CAA), respectively, under the conditions of the far-field assumption of the observation point and the actual condition. Furthermore, the effect of far-field hypothesis on the solution of Green's function is analyzed. The results show that for observation points in different directions, the deviation of solution of accompanying Green's function caused by far-field hypothesis is different. And for the observation point closer to the direction of the central line of the jet, the deviation caused by the far-field assumption is greater. The maximum deviation of the Green's function calculation results is above -15dB when the observation point in the 150 掳direction is adopted. For the noise observation points near the central line of the jet, in order to avoid the prediction deviation, the actual observation conditions should be used to solve the jet Green's function.
【作者单位】：北京航空航天大学能源与动力工程学院;
【基金】：国家“973”计划(2012CB720201) 国家自然科学基金(51476005)~~
【分类号】：V231.3

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