Laser-Assisted Prediction of Acoustic Radiation and Scattering

Sean F.Wu，P.I.Wayne州立大学NSF提案编号0084723激光辅助预测声辐射和散射项目摘要本研究旨在开发一种高精度和高效的方法来预测任意对象的声辐射和散射。非侵入式三维激光多普勒测速仪(LDV)被用来扫描和测量悬浮颗粒在完全封闭结构的控制面上的非电离流体介质中的速度矢量。将测得的速度矢量作为输入，建立显式积分公式，计算声压场。这种方法的优势在于：(1)它将现场声压与质点速度分布直接相关；(2)它提供了所有频率下声压的独特解决方案；(3)它使人们能够方便地解决瞬态声辐射问题。这项新技术在预测任何结构的声辐射和散射方面都有应用。特别是，它适用于柔性或轻质结构，或不允许传统接触测量装置的结构。该项目由韦恩州立大学机械工程系和电气与计算机工程系联合开展。这项联合研究对计算声学有着深远的影响。它有望彻底改变目前计算任意物体的声辐射和散射的方法，并显著提高数值计算的效率。对于必须考虑流体加载效应的复杂结构而言，情况尤其如此。这项新技术的应用可以在水下或地面飞行器产生的声场分析中找到。使用这种新方法，工程师可以评估飞机机舱或车辆乘客舱内的噪音传播性能，或车辆经过的噪音水平。由此获得的知识将使他们能够以具有成本效益的方式处理飞机和车辆的振动和噪音问题。

Sean F. Wu, P.I.Wayne State UniversityNSF Proposal No. 0084723Laser-Assisted Prediction of Acoustic Radiation and ScatteringProject AbstractThis research aims at developing a highly accurate and efficient methodology for predicting acoustic radiation and scattering from an arbitrary object. A non-invasive three-dimensional laser Doppler velocimetry (LDV) is used to scan and measure velocity vectors of suspended particles in an insonified fluid medium over a control surface that completely encloses the structure under consideration. The measured velocity vectors are taken as input to an explicit integral formulation to calculate the acoustic pressure field. This methodology is superior in that: (1) it correlates the field acoustic pressure directly to the particle velocity distribution; (2) it provides unique solutions for acoustic pressures in all frequencies; and (3) it enables one to solve transient acoustic radiation problems conveniently. Applications of this new technology can be found in predicting sound radiation and scattering from any structure. In particular, it is suitable for a flexible or lightweight structure, or for a structure that does not allow for conventional contact measurement devices. This project is carried out jointly between Mechanical Engineering Department and Electrical & Computer Engineering Department of Wayne State University. This joint research has a far-reaching impact on computational acoustics. It is expected to revolutionize the current way of calculating acoustic radiation and scattering from an arbitrary object, and significantly improve the efficiency in numerical computations. This is especially true for a complex structure for which the fluid-loading effect must be considered. Applications of this new technology can be found in the analyses of the sound field generated by an underwater or ground vehicle. Using this new method, engineers can assess the performance of noise transmission into an aircraft cabin or vehicle passenger compartment, or vehicle pass-by noise levels. The knowledge thus gained will enable them to tackle aircraft and vehicle vibration and noise problems in a cost-effective manner.