流动管道内噪声源辐射声场数值预估

流动管道内噪声源辐射声场问题难度很大。该文给出了经实验考核的流动管道内声源辐射声场数值预估方法,并给出了圆管外声压级指向性系数图。利用这些图和简单公式,通过测量管外一点的声压级就可确定管内声源声功率。该文数值方法采用线化Euler方程,四阶MacCormack差分格式和Tam与Webb的无反射边界条件数值预估有流动的圆管出口辐射声场,并用声强扫描仪和声级计在半消声室中测量了管内声功率及管外声压分布,数值计算和实验所得声压指向性系数符合良好,最大误差小于1dB。

Numerical prediction of the sound field radiated by noise sources in a duct with flow

The sound field radiated by noise sources in a cylindrical flow duct is so complicated that it has not yet been solved analytically. This paper presented a numerical method that was verified experimentally to predict the sound field. Figures are given for the direction coefficients of the sound pressure level (SPL) outside the duct for engineering applications. The figures can be used to easily calculate the sound power level of the sound source inside the duct through measuring the SPL at a single point outside of the duct. The sound field was numerically simulated using the linearized Euler equations, a fourth-order MacCormack finite difference scheme and Tam and Webb's non-reflection boundary conditions. The experiments in a semi-anechoic room used a scanning sound intensity meter to measure the sound power inside the duct and the sound pressure distribution outside the duct. The numerically determined SPL direction coefficients agree well with the measured data, with a maximum error within 1 dB.