圆孔声学非线性效应的数值模拟

本文发展了一种离散涡模型，模拟了在高声强声波作用下圆孔处发生的涡脱落过程。进而计算了圆孔中的声质点速度，并分析了孔中速度的畸变情况、最后给出了圆孔的非线性声阻和声抗的理论值。非线性声抗的理论预测是现有的研究圆孔声学非线性效应的准稳态模型没有满意解决的问题，因而所做的有关尝试是本文工作的特点之一。

NUMERICAL SIMULATION OF THE ACOUSTICNONLINEARITY OF AN ORIFICE

An axisymmetric discrete vortex model is developed in this paper in an attempt to give more understanding of the acoustic nonlinearity of an orifice. First, the vortex shedding process produced by high-amplitude incident sound is numerically simulated. Furthermore, the time history and spectrum of the average flow velocity through an orifice are computed, from which the nonlinear distortion of flow velocity is analyzed. Finally, an effort is made to give prediction of the nonlinear acoustic impedance over a large range of the sound pressure amplitude. One advantage of the present model is in the prediction of the nonlinear acoustic reactance, which is not well solved in the previous quasi-steady models.