摘要
降低噪声是民用飞机适航性的要求,降低飞机噪声必须控制飞机的主要噪声源发动机噪声向外辐射。飞机的主要噪声源为发动机,对于高速发动机,离散噪声占主导地位,在管道内以模态形式传播。对于超声速风扇,除了离散噪声,还有叶片与超声速来流相互作用形成的激波噪声,主要分布在叶片轴频率及其谐波处。本文主要通过在风扇试验件上开展声学测试获得声源的模态信息和管道内激波噪声轴向衰减特性,用于验证声模态和激波噪声分析工具。试验是在几种不同风扇工况下进行的,用布置在进气道中轴向不同位置的两圈传声器进行测量,周向各均布40个传声器,得到周向模态信息。在同一周向位置沿轴向布置10个传声器,用于获得激波轴向衰减。为能在试验中准确地量化各个测量值,并真正反映风扇管道声源特征,需要规范频谱处理的方法以及对高速风扇管道的声源有深刻的了解。本文阐述了管道声模态的基本理论,对管道内声模态的测量值进行了分析,最后跟数值结果进行对比,得到了较一致的结果。根据经验模型,激波主要分布在1BPF以内的轴频处,对试验数据展开分析,获得激波声功率级,与数值计算结果进行了对比分析,发现了试验中存在的问题,同时分析了幅值差异产生的原因。
Noise reduction is an important demand on civil airplane navigability,and it is also the need of military airplane stealth.The main noise source of aircraft comes from aero-engine.So it is necessary to reduce the noise radiation from aero-engine as the main noise source to reduce the noise from airplane.For high speed engine,the disperse noise is dominant.For supersonic fan,besides discrete noise,it appears shock noise because of interaction between fan and supersonic flow,which is mainly distributed at the shaft frequency and its harmonic frequency.As a main part of this thesis,the duct acoustic experiments are carried out in the fan rig to verify the analysis tool.The experiments are carried out in several different work conditions of fan,the acoustic mode is measured in duct by 40 microphones which is circumferential uniform at two axial location,at the same time the shock noise is measured in duct by 10 microphones which is axial arrangement at the same circumferential location.It is very important to have a good understanding of the proper method of frequency spectrum analysis and noise sources and noise propagation in high speed fan duct,because they could help to measure the noise level more accurately and show the characteristics of ducted fan noise sources and propagation more clearly.The theory of duct acoustic mode are presented in this paper,furthermore,the acoustic mode measurement is carried out to have some comparison with simulation result which obtains a consistent result.According to the empirical model,the shock noise mainly distributes in shaft frequency within 1BPF,data analysis is carried out to obtain the sound power level of shock noise which is used to compare with simulation result,and the problem of test is found,the reason of amplitude error is also analyzed.
作者
夏烨
陆美慧
李旦望
纪良
Xia Ye;Lu Meihui;Li Danwang;Ji Liang(AECC Commercial Aircraft Engine Co.,Ltd.,Shanghai 201108,China;Shanghai Center of Research for Commercial Aircraft Engine Engineering Techniques,Shanghai 201108,China)
出处
《航空科学技术》
2022年第8期16-22,共7页
Aeronautical Science & Technology
关键词
发动机
风扇
声模态
激波
测试
engine
fan
acoustic mode
shock noise
test
