加环筋轴对称壳体振动声辐射特性

为了研究加环筋轴对称壳的声振特性,建立了轴对称壳水中声辐射计算的FEM/BEM(有限元法/边界元法)三维模型,探索了加筋的高度、宽度、数目对轴对称壳的表面平均振速、辐射功率、辐射效率、激励点法向声强以及声场指向性的影响规律。计算方法是在有限元软件ANSYS中建模和模态分析基础上,将有关数据(网格、模态)导入边界元软件SYSNOISE中计算流体-结构耦合状态下的辐射声场特性。结果表明:随着环筋高度、宽度和数目的增大,激励点法向声强、表面平均振速、辐射效率和辐射声功率随频率变化曲线的峰彼此错开;环筋高度、宽度和数目增大时,激励点法向声强以及辐射声功率都有增加,而表面平均振速减小,因而导致声辐射效率的增加;在频率0~700 Hz内,低频时环筋高度、宽度和数目的变化对声场指向性影响规律类似;高频(601 Hz)环筋增多时对称壳尾部声辐射相对增强,而加筋处的中部声辐射相对减弱。

Characteristics of vibration and sound field of axisymmetric shell with stiffening rings

In order to investigate the characteristics of the vibration and sound field radiated by an axisymmetric shell with stiffening rings,a 3D model based on FEM/BEM for computing the sound field radiated by an axisymmetric shell with stiffening rings in water was established,and the effects of the height,the width and the number of the ring stiffeners on the roop mean square vibrational velocity,sound radiated power,radiation efficiency,normal sound intensity at driving point and pressure directivity of sound field radiated by it were investigated.The meshing data and modal data of the model in vacuo obtained from FEM code ANSYS were put into BEM code SYSNOISE and used for computing the parameters of the coupled sound field.The results show that: the curve peaks of the roop mean square vibratory velocity,radiated sound power,radiation efficiency,normal sound intensity at driving point will shift to different places when the width,or the height or the number of the stiffening rings increases;with the increase of the width,or the height or the number of the stiffening rings,the normal sound intensity at driving point and sound radiated power increases,the roop mean square vibratory velocity decreases,and the radiation efficiency increases;in the frequency region 0~700 Hz,the influence of the width,the height and the number of the rings on the sound field directivity pattern are nearly same,but at high frequency the number of rings makes the sound radiation from the tail higher than that from the middle section.16 figs,8 refs.