Bluff-body wakes and fluid-structure interactions

钝体尾流和流固相互作用

• 批准号: RGPIN-2018-03760
• 负责人: Sumner, David
• 金额: $ 1.97万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681779
• 关键词: Bluff; body; wakes; fluid; structure

The non-streamlined shape of a "bluff body" causes it to experience high aerodynamic drag forces or wind loading. The body's complex flow field is characterized by flow separation (where the flow does not follow the shape of the body), vortex formation from the body surface, interactions between shear layers (thin regions of fluid across which there are large changes in flow velocity), and an unsteady low-pressure wake behind the body. The phenomenon of "vortex shedding" occurs as vortices are released periodically from the body into the wake; under certain conditions, this may cause unwanted structural motion or "flow-induced vibration" (FIV).******Examples of bluff bodies include buildings, chimney stacks, bridge pylons, offshore structures, trains, road vehicles, rooftop-mounted equipment, and electronic components on circuit boards. The study of bluff-body flows is motivated by industrial problems related to FIV, flow-induced noise, dispersion of pollutants in the atmosphere, and cooling of electronic components. Flow around a bluff body becomes more complex when it is located near other bodies and structures, such as in groups of buildings, oil storage tanks, or stacks, and when the bluff body is "surface-mounted" and of "finite-height". In the latter case, the local flow fields at the surface and over the "free end" of the body strongly influence the wind loading and the tendency towards FIV. Preventing FIV, designing flow control strategies (to mitigate vortex shedding, for example), and implementing methods for drag reduction (to improve the fuel efficiency of a vehicle, for instance), require a good physical understanding of the "fluid-structure interactions" (FSI) for the flow around bluff bodies. The complex nature of these flows, however, poses significant challenges for field measurements, laboratory experiments, and computer simulations.******The main objective of the research program is to improve the fundamental physical understanding of the flow around surface-mounted finite-height bluff bodies (such as finite cylinders and prisms), primarily through wind tunnel experiments but secondarily with computational fluid dynamics. The program will involve the training of MSc, PhD, and undergraduate students. Specific interests of the research program include (i) answering fundamental questions related to the effects of aspect ratio, body shape and orientation, and the boundary layer on the surface; (ii) identifying "critical" conditions where there are marked changes in the flow patterns and forces; (iii) exploring wake and proximity interference effects for small groups of surface-mounted finite-height bluff bodies; (iv) understanding the effectiveness of passive flow control devices for these bodies; and (v) discovering the effects of structural motion (as related to FSI and FIV) on the wake flow patterns.

“悬崖主体”的非流线形状导致其经历高空气动力的阻力或风载。人体的复杂流场的特征是流动分离（流动不遵循身体的形状），从人体表面形成涡流，剪切层之间的相互作用（流动速度的较薄的流体区域很大变化） ，并且不稳定的低压在身体后面醒来。 “涡旋脱落”的现象是随着涡流从体内释放到尾流的。在某些条件下，这可能会导致不必要的结构运动或“流动引起的振动”（fiv）。******虚张声势的例子包括建筑物，烟囱堆栈，桥梁塔，桥梁塔，离岸结构，火车，道路车辆，屋顶车辆，屋顶车辆，屋顶车辆，安装的设备和电路板上的电子组件。悬崖体流的研究是由与FIV，流动诱导的噪声，大气中污染物的分散以及电子组件冷却相关的工业问题的动机。当悬崖的身体位于其他物体和结构附近，例如建筑物，储油罐或堆栈，而悬崖主体则“表面上”和“有限高度”时，它会变得更加复杂。 。在后一种情况下，表面和身体“自由端”的局部流场强烈影响风和FIV的趋势。防止FIV，设计流程控制策略（例如，减轻涡旋脱落），并实施减少阻力的方法（例如，提高车辆的燃油效率）需要对“流体结构相互作用”的物理理解， （FSI）围绕悬崖的流动。但是，这些流的复杂性质对现场测量，实验室实验和计算机模拟提出了重大挑战。有限高度虚张声势的主体（例如有限的圆柱体和棱镜），主要是通过风洞实验，但其次是通过计算流体动力学进行的。该计划将涉及MSC，PhD和本科生的培训。研究计划的特定兴趣包括（i）回答与纵横比，身体形状和方向的影响以及表面边界层有关的基本问题； （ii）确定流动模式和力发生明显变化的“临界”条件； （iii）探索一小组表面安装的有限悬崖主体的唤醒和接近性干扰效应； （iv）了解这些身体的被动流控制装置的有效性； （v）发现结构运动（与FSI和FIV相关）对尾流模式的影响。