Actively Controlled Hood for Machinery Noise

针对机械噪音的主动控制罩

• 批准号: 9060646
• 负责人: John Cole
• 金额: $ 4.86万
• 依托单位: Cambridge Acoustical Associates Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 1991-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9060646&HistoricalAwards=false
• 关键词: Actively; Controlled; Hood; Machinery; Noise

This project addresses the active control of noise for machinery. In most cases, passive control, by means of acoustical hoods, is used to reduce noise. Some applications include manufacturing machines in industrial environments, and heating, ventilating and air conditioning systems in office or residential spaces. In passive control, the hood is designed to attenuate the interior sound field by providing for acoustical damping in the air cavity and for structural damping in the enclosure walls. The performance achieved using these techniques is limited by constraints of volume, weight, and cost. On the other hand, the active control approach applies to the design of a closed loop feedback controller where issues of time delays, stability, and bandwidth are important. This project's approach is to design an enclosure structure that is as close to a stiff membrane as possible. Such a structure's response is dominated by supersonic structural modes. Cancellation of exterior noise is obtained by minimizing the normal response along the enclosure surface. This approach will be tested and compared with existing active control strategies. This approach's expected advantages include reduction of the number of surface sensors required to observe the response of the enclosure walls, and spatial filtering which insures rejection of excitation by shorter wavelength disturbances.

该项目旨在对噪声进行主动控制， 机械. 在大多数情况下，被动控制，通过 隔音罩用于降低噪音。 一些 应用包括工业中的制造机器 环境、供暖、通风和空调 办公室或住宅空间的系统。 被动 控制，引擎盖的目的是削弱内部 通过在空气中提供声阻尼的声场 空腔和用于外壳壁中的结构阻尼。 使用这些技术实现的性能是有限的 受体积重量和成本的限制。 另 一方面，主动控制方法适用于设计 闭环反馈控制器，其中时间问题 延迟、稳定性和带宽是重要的。 这 项目的方法是设计一个封闭结构， 尽可能接近硬膜。 这样的 结构的响应主要受超声速结构的影响 modes. 通过以下方式消除外部噪声： 使沿外壳表面的法向响应沿着最小化。 将对这种方法进行测试，并与现有的 主动控制策略。 这种方法的预期 优点包括减少表面的数量 观察外壳响应所需的传感器 墙，和空间过滤，确保拒绝 激发较短波长的干扰。