开式叶轮气动噪声信号离析方法和运用

比较了同工况下开式叶轮气动噪声声压信号的测量结果,发现不论是在时域还是在频域上都存在较大的浮动。若采用旋转机械常用的时域同步平均法处理噪声信号,不仅需要另外安装锁相装置,还会过滤了宽频噪声信号以及使得其它非谐频信号的幅值失真。为了离析出稳定且正确的开式叶轮气动噪声信号,本文提出了一种无须安装锁相装置同时又能解决上述问题的信号处理方法,并从理论和实际运用中验证此方法的可行性。进一步分析了开式叶轮气动噪声尖峰间距特征和叶片固有频率对噪声幅值的影响。为了避免物理设备的误差,本文提出用尖峰区域下的占空比来区分旋转噪声和宽频噪声,在此基础上,计算了旋转噪声的能量在气动噪声中所占的比例和在频域下旋转噪声的能量分布。

Application and Method on Separation of Open Rotor Aerodynamic Noise

In comparison with measurement results of open rotor sound pressure sign,whether in frequency domain or in time domain,there is much fluctuation in those results. If by the method of time synchronous averaging,not only locking phase equipment will be fixed addinally,but also broadband noise sign can be filtered and the sign of harmonic frequency except times rotating frequency will be of distortion. In order to extract steady and true sign from rotor aerodynamic noise,this paper introduces a simple and practical method without locking phase equipment,which can solve above mentioned problems. Then the method is proved to be true in theory and application analyses. What's more,the following problems are analyzed in this paper: a distance between peeks of noise keeping a some value and how to effect noise amplitude by blade natural frequency. To avoid physical equipment error,rotating noise is able to be distinguished from broadband by computing duty ratio. On the basis,those are computed: a energy ratio of rotating noise to broadband noise and energy distribution rule with noise blade passing frequency domain.