Actively Controlled Hood for Machinery Noise

本研究的第一阶段研究了 机械外壳作为噪声控制的应用， 主动取消减少噪音通过 结构是一种广泛存在于各种情况下的需要。 在这种方法中，实现了低频噪声的降低 通过主动控制的概念，并在高频率-使用被动 控制控制的性能估计表明需要 用于多个致动器以消除外壳传输的噪声 在整个主动控制频率范围内， 空间角度谱。在该研究项目的第二阶段， 重点是发展分析和数值模型， 三维围栏和评估的作用， 实现低成本目标的结构参数， 频率噪声滤波器;评估表面观测器选项; 开发用于驱动表面的具有成本效益的方法 评估备选传感器和设计概念 将它们嵌入面板模块;开发特定的 包括主要结构和 表面模块与传感器和执行器;和实验 使用原型外壳评估上述概念。*//

Phase I of this study had examined the design characteristics of machinery enclosures as an application for noise control by active cancellation. Reduction of noise transmitted through structures is a need that pervades a wide variety of situations. In this approach, noise reduction at low frequency is achieved via active control concepts, and at high frequency--using passive control. Performance estimates for control demonstrate the need for multiple actuators to cancel enclosure transmitted noise throughout the active control frequency range over the full spectrum of spatial angles. In Phase II of this research project, the emphasis is on developing analytical and numerical models of three-dimensional enclosures and assessing the role of structural-parameters in achieving the objectives of a low- frequency noise filter; evaluating surface observer options; developing cost-effective approaches for actuating the surface panels; evaluating alternative sensors and design concepts for embedding them into a surface panel module; developing a specific design for a prototype enclosure including primary structure and surface modules with sensors and actuators; and experimentally evaluating the above concepts using the prototype enclosure.***//