High-speed centrifugal blower for experimental aeroacoustics

用于实验气动声学的高速离心鼓风机

• 批准号: 407546-2011
• 负责人: Mohany, Atef
• 金额: $ 1.1万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments - Category 1 (<$150,000)
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=472657
• 关键词: speed; centrifugal; blower; experimental; aeroacoustics

The vortex-shedding phenomenon has been a subject of research since it was observed by Leonardo da Vinci. Vortex shedding occurs due to the boundary layer separation around bluff bodies in cross-flow. The boundary layer separates into two shear layers that trail and roll-up in the near field forming a periodic vortex street. In the case of a duct containing a bluff body such as a circular cylinder, when the vortex shedding frequency coincides with one of the acoustic natural frequencies of the duct, a feedback cycle may occur where the vortex shedding acts as a sound source and excites an acoustic standing wave which, in turn, enhances the shedding process and thereby creates a strong acoustic resonance. This process is known as flow-excited acoustic resonance. In many engineering applications where ducts containing clusters of bluff bodies are encountered, such as tube bundles of heat exchangers and boilers, cascades of compressor blades and guide/turning vanes in ducts and radial diffusers, unfortunate operating conditions could lead to a coincidence between the vortex shedding frequency and one of the acoustic natural frequencies of the duct. This often leads to flow-excited acoustic resonance and the generation of acute noise problems and/or excessive vibrations. Since this phenomenon is not yet fully understood, it can be dangerously unpredictable and may cause catastrophic failures in many applications such as power generation and transport. The main objective of the applicant's research in this area is to understand the feedback cycle of the flow-excited acoustic resonance. This requires the generation of a self-excited acoustic resonance in flow configurations similar to those mentioned above. However, the self-excited acoustic resonance will not materialize unless the flow velocity is sufficiently high to overcome the losses due to acoustic damping.This can only be achieved using the requested centrifugal blower system, which is capable of producing air flow with a velocity as high as 220 m/s in a cross-section area of 10 inch (25.4 cm) by 10 inch (25.4 cm).

自从列奥纳多达芬奇观察到旋涡脱落现象以来，它一直是研究的主题。在横流中，海崖体周围的边界层分离会导致旋涡脱落。边界层分离成两个剪切层，它们在近场中拖曳并卷起，形成周期性的涡街。在包含诸如圆柱体的非海崖体的管道的情况下，当涡旋脱落频率与管道的声学固有频率之一一致时，可能发生反馈循环，其中涡旋脱落充当声源并激发声学驻波，声学驻波又增强脱落过程，从而产生强烈的声学共振。这个过程被称为流动激励声共振。在许多工程应用中，遇到含有海崖体簇的管道，例如热交换器和锅炉的管束、压缩机叶片的叶栅以及管道和径向扩散器中的导向/转向叶片，不利的操作条件可能导致涡流脱落频率与管道的声学固有频率之一重合。这通常导致流激声共振和产生严重的噪声问题和/或过度振动。由于这一现象尚未完全了解，它可能是危险的不可预测的，并可能在许多应用中造成灾难性的故障，如发电和运输。申请人在该领域的研究的主要目标是理解流激声共振的反馈循环。这需要在类似于上述的流动配置中产生自激声共振。然而，除非流速足够高以克服由于声阻尼引起的损失，否则自激声共振将不会实现，这只能使用所要求的离心鼓风机系统来实现，该离心鼓风机系统能够在10英寸（25.4 cm）× 10英寸（25.4 cm）的横截面面积中产生具有高达220 m/s的速度的气流。