船用离心风机内部流动诱发蜗壳振动的数值研究

Numerical Investigation of Internal Fluid-induced Volute Vibration in a Marine Centrifugal Fan

针对船用离心风机内部非定常流动诱发蜗壳结构振动响应,发展了一种数值计算方法,该方法首先通过风机内部非定常流场计算获得振动激励源,其次采用流固弱耦合算法实现节点的插值和载荷加载,最后基于有限元的模态叠加法得到蜗壳结构动力响应。流场压力脉动和振动计算结果和实验测试结果分别做了对比,结果吻合较好,表明本文的方法能较准确地模拟叶轮机械内部流动诱发外部壳体的振动响应。从流场和振动响应两个方面阐述了流动诱发振动的机理:基频的非定常气动力是流固耦合振动的主要激励源,基频分量在振动的频率响应函数中占据主导地位,蜗壳的最大振动响应是基频下的非定常气动力和基频振动模态共同作用的结果。

A numerical method for casing structural vibration in a marine centrifugal fan was presented. Firstly, an unsteady flow field calculation of centrifugal fan was employed to obtain the vibration sources of volute casing; then a weak fluid-structure coupling algorithm was used for grid interpolation and loading aerodynamics loads; at the last, the volute structure vibration response was obtained based on the mode superposition method of FEM. Numerical results of pressure fluctuations in the flow fields and vibration responses are compared with experiments respectively, showing a good agreement. The mechanism of fluid-induced structural vibration was discussed through pressure fluctuations in the fluid fields and structural vibration responses, the pressure fluctuations of BPF are the primary exciting source of fluid-structure vibrations, BPF component is predominant in vibration frequency response. The major structural vibration response of volute casing results from contributions of both unsteady aerodynamics and vibration modal in BPF.