中文摘要：

本文发展了计算包含旋流的圆环形管道声传播问题的有限元数值模型，并且对等熵和均熵流动做了讨论。经典的声学有限元方法大多求解只包含一个变量的对流波动方程，但是对于包含旋流等非均匀流的圆环形管道声传播问题，不能简化成只含有一个变量的对流波动方程。本文尝试用直接求解耦合方程组的有限元方法方法研究管道声传播问题。文章分别研究了刚性壁面、不同阻抗的声衬壁面对管道声传播的影响，同时还对不同阶的声模态包括传播模态和截止模态在管道中的传播规律做了分析。计算的结果和正模态解析方法符合得很好，从而验证了有限元模型的正确性和可行性。

英文摘要：

An FEM model of studying sound propagation in annular duct with mean swirling flow is developped in this paper, and shows a discussion about homoenropic and isentropic flows. Classical FEM can be applied to solve single governing equation with one variable, but for the model of sound propagation in annular duct with ununiform mean flow such as swirling flow, the governing equations cannot be simplified. A method of solving coupled equations for sound propagation study of ducts is proposed. The paper gives a show of the effects of different impedance of liner on sound propagation, and we also study sound propagation rules of different modes including cut-on and cut-off modes. Through the comparison of results from FEM and normal mode analysis method, the FEM model has been proved.