考虑边界层效应的进气道声衬最优阻抗的快速预测方法研究  

Study on Quick Prediction of Optimum Acoustic Impedance of Engine Intake Liner With Boundary Layer

作　　者：邵卫东 李旦望 SHAO Wei-Dong;LI Dan-Wang(AECC Commercial Aircraft Engine Co.,Ltd.,Shanghai 200241,China;Shanghai Key Laboratory of Aircraft Engine Digital Twin,Shanghai 200241,China)

机构地区：[1]中国航发商用航空发动机有限责任公司,上海200241 [2]上海市航空发动机数字孪生重点实验室,上海200241

出　　处：《工程热物理学报》2021年第5期1193-1199,共7页Journal of Engineering Thermophysics

基　　金：上海市青年科技英才杨帆计划资助项目(No.20YF1454200)。

摘　　要：在进气道内布置声衬可大幅降低大涵道比涡扇发动机的风扇前传噪声,对其声阻抗进行优化可进一步带来结构设计和空间布局上的收益;传统设计过程中针对最优声阻抗的预测没有考虑边界层效应,然而其对某些工况下的声吸收率误差达10 dB。为兼顾预测精度和计算耗时,本文发展了一种考虑边界层效应的最优声阻抗的快速计算策略:基于Brambley阻抗边界条件下线性化的欧拉方程的解,假设最低衰减模态的最大吸收率发生在圆管道模态归并点(野点),将声衬阻抗优化问题转化为寻找第一个野点对应声阻抗问题。采用该方法考查了不同平均流马赫数、边界层厚度、周向模态阶数和频率的影响,并与数值精确解及其他学者计算结果进行对比,结果证明了该方法的有效性,为将其推广到缓变进气道和多模态传播问题提供了参考。Laying liners in the engine intake can significantly reduce the forward propagating fan noise.Optimization of its acoustic impedance can further bring benefits in configuration and layout.For the traditional liner design,the boundary layer effect has not been taken into account.However,in certain conditions,the predictive error of acoustic absorption rate can be 10 dB.In order to balance accuracy and time cost,we develop a quick prediction model based on the solution of the linearized Euler equation with inviscid sheared flow.Assuming that the maximum acoustic absorption rate of the least attenuated modes occur at the exceptional points,the optimization of acoustic impedance is transferred into finding the first exceptional point.Moreover,the influences of mean flow Mach number,boundary layer thickness,circumferential wave number and frequency are studied.The results are compared with other exact solution,which demonstrates the effectiveness and stability.It also provides a promising extension to multi-modal propagation in slowly varying intake.

关 键 词：边界层 声阻抗 优化 进气道 

分 类 号：V211[航空宇航科学与技术—航空宇航推进理论与工程]