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.

游离剪切流，例如在悬崖尸体后面的唤醒，在腔和侧面分离的剪切层以及射流流穿过孔口和阀门，非常不稳定。自由剪切流的不稳定性会产生周期性的涡度脱落，其频率随流速而变化。在许多工业应用中是典型的湍流中，例如热交换器，锅炉植物，涡轮机，管道系统和反应堆容器中的管束，涡流脱落较弱且无组织/无组织/不一致。但是，当具有声学模式的涡度脱落夫妻时，反馈机制会发生，并且涡度脱落变得更强大，更相干。这导致产生的急性噪声问题通常与过度振动有关，这可能导致操作中断，在某些情况下可能会迅速升级为灾难性的失败。由于声学共振现象尚未完全理解，因此它可能是不可预测的。 拟议的研究的目的是提高流动相互作用机制的知识状态以及流动诱导的声音共振实现的条件。在研究计划的接下来的五年中，重点将放在两个主要流程配置上鳍圆柱簇（焦点区域II）。此外，将开发一个可用于预测管阵列中声共振发生的声学阻尼标准（焦点区域III）。拟议研究的发现将有助于应对几种重要的工业应用中流动引起的噪声和振动问题的突然激发有关的挑战，以及缺乏预测其在设计阶段发生的指南。由于潜在的灾难性故障，这不仅会减少这些工程应用计划外的计划，而且还可以构建更大，更安全，更高效的设备。