Bluff-body wakes and turbulent flows

钝体尾流和湍流

• 批准号: 217199-2013
• 负责人: Sumner, David
• 金额: $ 1.89万
• 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: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=570117
• 关键词: Bluff; body; wakes; turbulent; flows

"Bluff bodies" have non-streamlined shapes and very high drag coefficients. Flow around a bluff body is complex, and is characterized by a large region of separated flow, where the flow does not follow the shape of the body. In the low-pressure wake downstream of the body, which may be unsteady or turbulent, the phenomenon of "vortex shedding" occurs as vortices are periodically released from the surface of the body. Under certain conditions, vortex shedding may cause unwanted structural motion known as "flow-induced vibration." The main scientific goal of my research program is to advance the physical understanding of bluff-body wakes, where the emphasis is the flow around surface-mounted, finite-height bluff bodies, such as finite circular cylinders, finite square prisms, and rooftop-mounted chimney stacks. I want to better understand the fundamental relationships between the wake-generating body and the local flow field, and how the near wake is influenced by alterations to the body shape, its proximity to other bluff bodies, and the presence of the ground plane. For the rooftop-mounted stack (an "elevated jet in cross-flow"), I want to better understand how the stack jet flow regimes affect the forces experienced by the stack and the flow in the stack wake. A second scientific goal of my research is to better understand the effects of surface roughness on wall-bounded turbulent shear flows, specifically the plane turbulent wall jet. Turbulent wall jets are encountered in the film cooling of turbine blades and in slotted flaps on airplane wings. For this flow, I want to better understand the effects of surface roughness and Reynolds number on the skin-friction drag acting on the wall. For both main research areas, the expected research contributions will include new experimental data for engineering design work, and new knowledge into the fundamentals of fluid flow behaviour. Both experimental and numerical modeling approaches will be used in the research program.

“虚张声势”身体具有非流线形状和非常高的阻力系数。 围绕虚张声势的身体流动很复杂，其特征是大区域的流动，流动不遵循身体的形状。 在身体下游的低压唤醒中，可能是不稳定或湍流的，随着涡流从身体的表面定期释放，“涡旋脱落”的现象发生。 在某些条件下，涡旋脱落可能会导致不良结构运动，称为“流动诱导的振动”。 我的研究计划的主要科学目标是提高对悬崖身体唤醒的物理理解，在这种情况下，重点是围绕表面安装的，有限的空白虚张声势，例如有限的圆形圆柱体，有限的正方形棱镜和屋顶 - 安装的烟囱堆栈。 我想更好地理解尾流的身体与局部流场之间的基本关系，以及近尾流的影响如何受到对身体形状的改变，与其他悬崖主体的距离以及地面平面的存在的影响。 对于屋顶安装的堆栈（“跨流中的高架喷气机”），我想更好地了解堆栈喷气流程如何影响堆栈所经历的力和堆栈唤醒中的流动。 我的研究的第二个科学目标是更好地了解表面粗糙度对壁挂式湍流剪切流的影响，特别是平面湍流壁喷气机。 在涡轮刀片冷却和飞机翼上开槽的襟翼的薄膜冷却中遇到了湍流的墙喷头。 对于这种流程，我希望更好地了解表面粗糙度和雷诺数对作用在墙上的皮肤摩擦拖动的影响。 对于两个主要研究领域，预期的研究贡献将包括用于工程设计工作的新实验数据，以及对流体流动行为的基本面的新知识。 研究计划将使用实验和数值建模方法。