Investigation of Turbulent Flow Separation and the Development of Flow Control Strategies for Bluff Bodies in Ground Proximity

钝体(方形物体，如砖块或一些道路车辆)的流动分离和空气动力学在许多工业应用中都会遇到。流动分离的后果包括导致阻力、结构振动、噪音等不良影响的显著压力波动，以及工程系统效率和性能的显著降低。例如，众所周知，在高速行驶时，超过50%的燃料用于克服道路车辆的空气动力学阻力。由于上述原因，钝体空气动力学几十年来一直是一个热门的研究课题。然而，对于复杂的三维钝体，一些基本的问题还没有完全解决：如何准确地预测三维钝体上的阻力？拟议的研究有三个短期目标：i)详细描述一些三维钝体在地面附近的平均和脉动流动结构；ii)开发对三维钝体有效的先进流动控制策略，以及量化它们的力学参数；以及iii)开发精确的数值模型，以全面捕捉钝体上的完整空气动力学现象。为了满足短期目标，将建造各种三维钝体。然后，将使用粒子图像测速仪、热线、压力传感器和力传感器在风洞和水洞中的钝体周围进行速度、压力和力的测量。此外，将使用开放源码数值代码对这些研究采用数值技术。预计在未来5年内，将对16名HQP(3名博士、3名硕士和10名本科生)进行详细的实验和数值模拟，使他们能够对钝体空气动力学有一个透彻的物理理解。预计研究计划的成功完成将提供新的见解，以阐明我们对古老的基本问题的物理理解。这可以导致开发性价比高的流量控制装置，以提高工程系统的效率。它还将有助于减少加拿大的碳足迹及其对我们气候的影响。此外，HQP还将培养在学术界或对加拿大具有社会经济重要性的不同行业就业的有用技能。

Flow separation and aerodynamics of bluff bodies (objects with boxy shapes like bricks or some road vehicles) are encountered in many industrial applications. The consequences of flow separation include significant pressure fluctuations that cause undesirable effects such as drag, structural vibration, noise and significant reductions in efficiency and performance of engineering systems. It is well-known that at highway speeds, for example, more than 50% of the fuel is used to overcome aerodynamic drag on road vehicles. For the above reasons, bluff body aerodynamics has been a subject of intensive research interests for many decades. However, for complex three-dimensional (3D) bluff bodies, some fundamental questions are not fully resolved: how do we accurately predict the drag on a 3D bluff body? The proposed research has three short-term objectives: i) characterize in detail the mean and fluctuating flow structures of a number of 3D bluff bodies in ground proximity; ii) develop advanced flow control strategies that are effective for 3D bluff bodies, and mechanistic parameters for quantifying them; and iii) develop accurate numerical models for fully capturing the complete aerodynamic phenomena on the bluff bodies. In order to meet the short-term objectives, a variety of 3D bluff bodies will be constructed. Velocity, pressure, and force measurements will then be conducted around the bluff bodies in wind and water tunnels using particle image velocimetry, hotwire, pressure sensors, and force sensors. In addition, numerical techniques will be employed for these studies using open source numerical codes. It is expected that over the next 5 years, 16 HQP (3 PhD, 3 MASc, and 10 undergraduate students) will be trained to perform detailed experiments and numerical simulations to enable them to gain a thorough physical understanding of bluff body aerodynamics. It is anticipated that a successful completion of the research program will provide new insight to illuminate our physical understanding of age-old fundamental questions. This can lead to the development of cost-effective flow control devices to improve the efficiency of engineering systems. It will also help reduce Canada's carbon footprint and its impacts on our climate. Additionally, HQP will develop useful skills for employment in academia or diverse industries of socio-economic importance to Canada.