分散式速度反馈控制流激薄板声振响应的模态解及特性
Modal solution and characteristics of decentralized velocity feedback controlled flow-excited thin plate acoustic vibration response
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摘要: 采用模态展开法推导了湍流边界层和分散式速度反馈控制共同作用下薄板的响应和声辐射, 给出了与分散式速度反馈控制增益系数、单元位置、数量和大小相关的模态阻尼的显示表达式。给定激励和参数的条件下, 通过与元素法的计算结果进行对比, 验证了模态展开法具有较高的计算效率和准确性。讨论了分散式速度反馈控制单元的布置方式和数量对模态阻尼的影响, 以及反馈控制单元的布置方式对薄板动能、辐射声功率和模态平均辐射系数的影响。数值分析结果表明反馈控制单元的数量和布放位置对控制效果影响显著, 反馈控制单元沿螺旋线布置能明显拓宽控制频带; 两种反馈控制单元布置方式, 在动能和辐射声功率控制较好的共振频率处, 除第一阶模态外, 模态平均声辐射效率随反馈增益的增大明显提高。Abstract: The response and acoustic radiation of a turbulent boundary layer (TBL) induced thin plate under decentralized velocity feedback control are derived using the modal expansion method, in which an explicit expression for the modal damping related to the gain coefficient, unit location, number and size of the decentralized velocity feedback control is given. For the given excitation and parameters, the current approach was verified to have much higher computational efficiency in comparison with that of the finite unit method. The effects of the arrangement and number of decentralized velocity feedback control units on the modal damping, and the effects of the arrangement of the feedback control units on the kinetic energy and radiated sound power of the thin plate are discussed. The numerical analysis results show that the number and location of feedback control units have a significant effect on the control effect, and the arrangement of feedback control units along the helix can significantly broaden the control band, the average modal radiation efficiency of the two feedback control units increases with the increase of feedback gain except for the first mode at the resonant frequencies with better kinetic energy and radiated sound power control.