Flow-Sound Interaction Mechanisms with Application to Bluff Body Wakes and Separated Shear Flows

流声相互作用机制及其在钝体尾流和分离剪切流中的应用

• 批准号: RGPIN-2022-04031
• 负责人: Mohany, Atef
• 金额: $ 2.33万
• 依托单位: University of Ontario Institute of Technology
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=752807
• 关键词: Flow; Sound; Interaction; Mechanisms; Application

Free shear flows, such as wakes behind bluff bodies, separated shear layers over cavities and side branches, and jet flows through orifices and valves, are highly unstable. The instabilities of the free shear flows generate periodic vorticity shedding with frequencies that vary linearly with the flow velocity. In turbulent flow, which is typical in many industrial applications, such as tube bundles in heat exchangers, boiler plants, turbomachines, piping systems, and reactor vessels, the vorticity shedding is weak and highly unorganized/incoherent. However, when the vorticity shedding couples with an acoustic mode a feedback mechanism occurs and the vorticity shedding becomes stronger and much more coherent. This leads to the generation of acute noise problems that are often associated with excessive vibration, which could result in operation interruption and in some cases may escalate rapidly to catastrophic failures. Since the acoustic resonance phenomenon is not yet fully understood, it can be dangerously unpredictable. The objective of the proposed research is to advance the state of knowledge of the flow-sound interaction mechanisms and the conditions under which flow-induced acoustic resonances materialize. In the next five years of the research program the focus will be on two main flow configurations where bluff body wakes and separated shear flows are encountered to elucidate the fundamental mechanisms of flow-acoustic coupling in tube bundles (FOCUS AREA I) and resonance excitation from cluster of finned cylinders (FOCUS AREA II). Moreover, an acoustic damping criterion that can be used to predict the occurrence of acoustic resonance in tube arrays will be developed (FOCUS AREA III). The findings of the proposed research will help to tackle challenges associated with the sudden excitation of flow-induced noise and vibration problems in several important industrial applications and the lack of guidelines to predict their occurrence during the design stage. This will not only reduce unplanned shutdowns of these engineering applications due to potential catastrophic failures but also will allow for the construction of larger, safer, and more efficient equipment.

自由剪切流，如海崖体后的尾流，空腔和侧支管上的分离剪切层，以及通过孔口和阀门的射流，都是高度不稳定的。自由剪切流的不稳定性产生周期性的涡脱落，其频率随流速线性变化。在湍流中，这在许多工业应用中是典型的，例如热交换器、锅炉设备、锅炉、管道系统和反应器容器中的管束，涡度脱落是弱的并且高度无组织/不连贯的。然而，当涡量脱落与声学模式耦合时，反馈机制发生，并且涡量脱落变得更强且更连贯。这导致产生严重的噪音问题，这些问题通常与过度振动有关，这可能导致操作中断，在某些情况下可能迅速升级为灾难性故障。由于声学共振现象尚未完全理解，它可能是危险的不可预测的。 所提出的研究的目的是推进的知识状态的流声相互作用机制和条件下，流引起的声共振实现。在未来五年的研究计划的重点将是两个主要的流动配置，其中海崖体尾流和分离的剪切流遇到阐明的基本机制的流声耦合在管束（焦点区域I）和共振激励从集群的翅片圆柱（焦点区域II）。此外，还将开发一种可用于预测管阵列中声共振发生的声阻尼标准（重点领域III）。拟议研究的结果将有助于解决与几个重要工业应用中的流致噪声和振动问题的突然激励相关的挑战，以及在设计阶段缺乏预测其发生的指导方针。这不仅可以减少这些工程应用因潜在灾难性故障而导致的计划外停机，还可以建造更大、更安全、更高效的设备。