【作者】 杨昆；

【导师】 赵汉中；

【作者基本信息】 华中科技大学 ， 流体力学， 2004， 硕士

【摘要】 本文对无限水域中压电/弹性材料复合层球壳的声波反射进行了数值研究。目的是利用主动减噪方式降低球壳对声波的反射,即在复合层球壳的压电层中,加载合适的电压,使球壳在流场中某方向或某区域内的反射压强大大降低。文中利用ANSYS的多物理场分析模块建立有限元模型,实现了流-固-电的直接耦合振动分析,研究了复合层球壳对点声源的反射及其控制。首先计算了压电层短路(无压电控制)时球壳对点声源反射,得到流场中各结点的反射压强。然后找到使各结点反射压强为零所需加载的电压,进行分析。最后计算了在压电层上加载特定控制电压后,球壳对点声源的反射,得到控制后流场中各结点的反射压强,并与球壳压电层短路时的情况对比,由此给出了压电控制所得到的减噪效果。研究结果表明,在压电层中加载一个合适的控制电压,可以使球壳中心与点声源连线方向上,距离球壳足够远的点上的反射压强都降低为零或接近于零,并且在一个较大的锥形区域内反射压强明显降低。可以找到一个合适的控制电压,使流体区域内任一选定方向上距离足够远处的反射压强基本消除,并在以此方向为轴线,球壳中心为顶点的锥形区域内有明显的减噪效果。本文还通过大量的计算实例给出了减噪中各参数的影响规律。更多还原

【Abstract】 The acoustic reflection from a submerged piezoelectric/elastic bilaminar spherical shell is studied by the finite element method (FEM). It is supposed to diminish the reflection from the spherical shell by applying an appropriate controlled voltage potential across the piezoelectric shell which was known as an active acoustic control method.It is used the multiphysics module of the software ANSYS to establish the finite element model which combines elastic, piezoelectric, and fluid-loading effect. In this model the sphere is enclosed by infinite fluid and an acoustic point is fitted in the fluid. First calculate the reflection when the piezoelectric shell is short-circuit, we get the scatter pressure on each node. Then find the required electric potential to eliminate the scatter pressure on each node and study them. According to the studying, an appropriate voltage potential was selected and be loaded on. By calculating we get the reflection after controlled. Finally a comparison is made to find the efficiency in noise reduction. The numerical results show that applying an appropriate voltage potential across the piezoelectric shell can suppressing the far-field reflected pressure on the direction of the line linked the sphere core and the acoustic point. And the reflected pressure in a cone fluid field was reduced simultaneously. For any direction, an appropriate voltage can be found to suppress the far-field reflected pressure on it.更多还原