不同边界条件封闭空腔内噪声主动控制研究

Active Control of Noise in an Enclosure with Different Boundary Conditions

应用模态理论对两弹性壁封闭空腔内耦合声场进行建模,弹性壁边界条件分别采用简支和固支两种情况来讨论。由于不同边界条件对应的结构模态振型函数不同,因此腔内初级声势能峰的幅值和位置不同,而目标噪声的选取与势能峰的大小有关;同时,控制力的位置也通过优化的声势能轮廓图来设计。利用优化的控制力可实现对腔内噪声实施主动控制。研究表明两种边界条件确定的控制力对腔内声场的控制均取得了一定的降噪效果,但封闭空腔和确定控制力的边界条件一致时,目标噪声的控制效果明显好于两者边界条件不一致时的情况。因此,准确判断弹性壁之间的边界约束对初级声场特性分析及声场控制具有显著影响。

The coupling sound field in an enclosure with two elastic walls was modeled by the modal theory. The boundary conditions of elastic walls were discussed using simple support and clamped support, respectively. The amplitudes and positions of the primary acoustic potential energy peaks in the enclosure were different due to the different structural mode shapes corresponding to the different boundary conditions. The selection of target noise was related to the values of the potential energy peaks. Meanwhile, the position of the control force was also designed by the contour map of the optimal acoustic potential energy. The optimal control force was used to control the noise in the enclosure. The research shows that the control force determined by the two boundary conditions has achieved certain noise reduction effect on the control of the sound field in the enclosure. However, when the boundary condition of the enclosure and the determining control force are the same, the control effect of the target noise is obviously better than that when the boundary condition of both is inconsistent. Therefore, the accurate determination of the boundary constraint between the elastic walls has a significant influence on the analysis of the primary acoustic field and the control of the sound field.