基于Mohring声类比发动机喷流噪声数值计算  

Numerical Calculation of Engine Jet Noise Based on Mohring Acoustic Analogy

作　　者：闫国华[1,2] 冯叔阳 刘勇 李建福[3] YAN Guo-hua;FENG Shu-yang;LIU Yong;LI Jian-fu(School of Aeronautical Engineering,Civil Aviation University of China,Tianjin 300300,China;Basic Experiment Center Civil Aviation University of China,Tianjin 300300,China;Second Military Representative Office of Air Force Equipment Department Stationed in Shenyang Area,Shenyang 110043,China)

机构地区：[1]中国民航大学航空工程学院,天津300300 [2]中国民航大学基础实验中心,天津300300 [3]空军装备部驻沈阳地区第二军事代表室,沈阳110043

出　　处：《航空发动机》2023年第1期53-61,共9页Aeroengine

基　　金：中央高校基本科研业务费项目(3122019093);中国民航大学科研启动基金(2020KYQD76)资助。

摘　　要：为了研究非均匀流场中航空发动机喷流噪声特性,满足未来的航空器噪声适航要求,采用计算流体力学(CFD)和计算航空声学(CAA)相结合的混合数值算法,对大涵道比发动机喷管的简化缩尺模型进行气动噪声仿真计算。采用大涡模拟(LES)计算喷管的瞬态喷流流场;在流场计算的基础上使用Mohring声类比进行声源提取,将时均流场插值到声学网格作为背景流,结合有限元和无限元方法对喷流噪声近场以及远场的辐射特性进行数值计算及分析,并通过单通道锯齿形喷管试验验证数值计算方法的可行性。数值结果表明:发动机喷流噪声主要是由内外涵剪切层内的涡环破碎产生的大尺度涡而形成的,噪声辐射峰值主要集中在低频范围内,随着频率升高,各方向角的声压级都在降低,在1000~2500 Hz,从125 dB快速降低到105 dB,之后衰减速度变缓,到100 dB趋于稳定。数值计算方法精确度高,最大计算误差为1.97%。为发动机噪声适航提供了一种噪声预测方法。In order to study the characteristics of aeroengine jet noise in a non-uniform flow field,and meet future aircraft noise airworthiness requirements,a hybrid numerical algorithm combining Computational Fluid Dynamics(CFD)and Computational Aeroacoustics(CAA)was adopted.The simplified scale model of a large bypass ratio engine nozzle was calculated by the aerodynamic noise simulation method.The transient jet flow field of the nozzle was calculated using the LES(Large Eddy Simulation)method.Based on the flow field calculation,the sound source was extracted using the Mohring sound analog.The time-averaged flow field and its smooth interpolation were introduced to the acoustic grid as a background flow field.The near-field and far-field radiation characteristics of jet noise were numerically calculated and analyzed by combining finite element and infinite element methods.And the feasibility of the numerical calculation method was verified by the single-channel Chevron nozzle experiment.The numerical results show that engine jet noise is formed by large-scale vortices generated by the breaking of vortex rings in the inner and outer bypass shear layers.The peaks of noise radiation are concentrated in the low-frequency range.With the increase of frequency,the sound pressure level in each direction is decreasing,from 125 dB to 105 dB at 1000 Hz to 2500 Hz,and then the attenuation rate slows down and becomes stable at 100 dB.The numerical calculation method has high accuracy and the maximum calculation error is 1.97%,which can provide a noise prediction method for engine noise airworthiness certification.

关 键 词：分开排气喷管 高亚声速喷流 大涡模拟 Mohring声类比 喷流噪声 航空发动机 

分 类 号：V235.13[航空宇航科学与技术—航空宇航推进理论与工程]