INDUSTRIAL AEROACOUSTICS: PLANAR JETS AND CAVITY FLOWS

工程应用中的许多流动本质上是湍流的，因此会产生压力脉动。一个安全、高效、安静的流体力学装置的良好设计选择将这些压力脉动保持在可接受的低水平。然而，在一些涉及流动分离和再附着的情况下，如油漆和涂层过程中的撞击射流，或流过建筑穿孔板，流动湍流会产生强烈的压力脉动。例如，当气流的湍流激发了长笛“管”内的声波时，长笛就会发出悦耳的音调。当类似的现象在工业应用中发生时，产生的压力脉动比笛子的压力脉动要弱。它们可能足够强大，产生危险的过度振动，震耳欲聋的噪音水平或造成结构破坏，从而危及工作场所和邻近社区的安全和环境。即使当产生的噪声和振动水平足够低并且可以容忍时，制造产品的表面质量也会因压力脉动而下降。** **提出的研究的目的是推进知识的机制产生压力振荡的冲击流的状态。工作将集中在两个对工业应用很重要的通用流程案例上。在第一种情况下，研究了两个相对平面射流的振荡，并探讨了这些振荡对镀锌和涂漆物体边缘表面质量的影响。更好地了解这些现象将有利于加拿大汽车工业钢板的镀锌过程。这项工作的另一项任务是研究建筑行业中使用的穿孔板上的气流产生声音（噪音）的原因。这两个研究任务的结果将在设计指南中实施，以避免在设计阶段产生压力脉动，从而有助于提高这些通用流动情况的安全性和效率。此外，由于拟议的计划结合了基础调查和面向行业的研究，它将构成一个优秀的和有吸引力的高素质人才的培训基地。****

Many flows in engineering applications are turbulent in nature and therefore produce pressure pulsations. A good design of a fluid mechanics device, that is safe, efficient and quiet, opts to maintain these pressure pulsations at an acceptably low level. However, in some cases involving flow separation and reattachment, such as impinging jets in painting and coating processes, or flow over architectural perforated panels, the flow turbulence can generate strong pressure pulsations. An example would be the pleasant tones of the flute, which are produced when the turbulence of the air stream being blown excites the sound waves inside the flute "pipe". When similar phenomena occur in industrial applications, the resulting pressure pulsations are less benign than those of the flute. They can be sufficiently strong to generate dangerous excessive vibrations, deafening noise levels or cause structural failures and thereby endanger the safety and the environment of the work place and neighbouring communities. Even when the generated noise and vibration levels are sufficiently low and can be tolerated, the surface quality of the manufactured product can be degraded by the pressure pulsation.** **The objective of the proposed research is to advance the state of knowledge of the mechanisms generating pressure oscillations by impinging flows. The work will focus on two generic flow cases which are important for industrial applications. In the first case, the oscillations of two opposing planar jets are investigated and the effect of these oscillations on the surface quality at the edges of galvanized and painted objects is explored. Better understanding of these phenomena will benefit the galvanizing process of sheet steel for the automotive industry in Canada. The other task of the proposed work focuses on the cause of sound (noise) generation by flow over perforated panels used in the architectural industry. The results of both research tasks will be implemented in design guides to avoid the generation of pressure pulsation during the design stage to help improve the safety and the efficiency of these generic flow situations. Furthermore, since the proposed program combines fundamental investigations with industry-oriented research, it will constitute an excellent and attractive training ground for highly qualified personnel.****