Vortex dynamics and energy transfer in turbulent 3D bluff-body wakes.

湍流 3D 钝体尾流中的涡动力学和能量传递。

• 批准号: RGPIN-2014-03660
• 负责人: Martinuzzi, Robert
• 金额: $ 4.23万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=638915
• 关键词: Vortex; dynamics; energy; transfer; turbulent

Bluff-bodies are diagnostic simplifications for a wide range of flow geometries of industrial and environmental importance such as: free-standing structures (buildings, bridges, wind turbines); mixing devices (in combustors, chemical reactors or heat exchangers); rough and urban terrain. The flow separation process on the obstacle surfaces gives rise to highly energetic, large-scale regions of rotating and recirculating flow. These coherent flow structures interact, causing distortions of the velocity field leading to energy transfer to smaller but more intense motions, which travel downstream and are responsible for high levels of concentrated velocity fluctuations (turbulence), unsteady forces and enhanced mixing. The present program addresses fundamental and applied challenges for understanding these flows and designing devices: the development of robust and statistically objective techniques to characterize unsteady flow behaviour, the formulation of a mathematical framework for modelling and controlling these flows; and a fundamental understanding of how geometry and incident flow conditions affect the flow physics.The five-year research objectives are to understand and control the dynamics of turbulent wakes for surface-mounted bluff-bodies; focusing on the influence of the incident boundary layer, obstacle geometry and tip-flow interactions on turbulence characteristics and flow evolution. This work is underpinned by the development of generalized diagnostic conditional averaging techniques to objectively represent coherent and turbulent motion. This approach sets the basis for dynamically consistent reduced-order mathematical models to investigate energy transfer and flow control strategies.The outcomes of this program are important scientific and engineering advances relevant to fundamental studies and practice. The research addresses prediction and control. The proposed experiments are heuristic simplifications designed to provide insights in the underlying physics of wake flows pertinent to flow-devices, fluid-structure interactions, mixing processes and environmental safety. The generalized conditional averaging methodology permits novel, dynamically consistent approaches for analysing unsteady flow behaviour by separating deterministic (coherent) and stochastic (turbulent) energetic contributions. The resulting representation, for example, improves the accuracy of unsteady-load predictions and yields new insights to guide turbulence model development. This approach can be extended to studies of structural dynamics and noise generation. The reduced-order formulation is a cornerstone of flow control strategies, e.g. to suppress noise generation or stall on compressor or wind turbine blades. This technique can improve design practice by providing a rapid interactive visualisation tool, capable of isolating and modelling engineering relevant flow quantities, without recourse to extensive and time-consuming simulation procedures. In this program highly qualified personnel are trained in state-of-the-art optical techniques, remote-sensing technologies, mathematical and computational tools. The focus is to develop a strong expertise in fluid mechanics fundamentals and their applications to industry driven engineering developments. The interdisciplinary nature of the training is supplemented by international and national collaborations. This strategy aims to develop independent engineers, with sound critical judgment and flexible skills.The program’s potential benefits to Canada are: increased industry competitiveness and lower greenhouse gas emissions (e.g. improved aircraft engine and wind turbine performance); wind-damage mitigation; new technologies and advanced training of highly qualified personnel.

悬崖体是针对工业和环境重要性的各种流量几何形状的诊断简化，例如：独立的结构（建筑物，桥梁，风力涡轮机）；混合装置（在战斗机，化学反应堆或热交换器中）；粗糙和城市地形。障碍物表面上的流动分离过程会导致高能旋转和循环流的高度大规模的区域。这些相干的流量结构相互作用，导致速度场的扭曲，导致能量转移到较小但更激烈的运动，这些动作下游传播，并导致高水平的浓缩速度波动（湍流），不稳定的力和增强的混合。目前的程序涉及理解这些流和设计设备的基本和应用挑战：强大和统计学上客观的技术的开发以表征不稳定的流动行为，这是建模和控制这些流的数学框架的公式；对几何和入射流条件如何影响流动物理的基本理解。五年的研究目标是了解和控制湍流唤醒的动力学，以表面安装的悬崖化体。专注于入射边界层的影响，障碍物几何形状和尖端流相互作用对湍流特征和流动进化的影响。这项工作的基础是开发通用的诊断有条件平均技术，以客观地代表连贯和湍流的运动。这种方法为动态一致的减少阶数模型奠定了基础，以研究能量传输和流控制策略。该计划的结果是重要的科学，工程学的进步与基本研究和实践有关。该研究解决了预测和控制。拟议的实验是启发式简化，旨在提供与流动设备，流体结构相互作用，混合过程和环境安全有关的尾流物理学的见解。通用的条件平均方法允许通过分离确定性（相干）和随机（湍流）能量贡献来进行新颖的，动态一致的分析流动行为。例如，由此产生的表示提高了不稳定的预测的准确性，并产生了新的见解以指导湍流模型的发展。这种方法可以扩展到结构动力学和噪声的研究。降级公式是流量控制策略的基石，例如抑制在压缩机或风力涡轮机叶片上产生噪音或失速。该技术可以通过提供快速的交互式可视化工具来改善设计实践，该工具能够隔离和建模工程相关的流量数量，而无需求助于广泛且耗时的模拟程序。在此计划中，高素质的人员接受了最先进的光学技术，遥感技术，数学和计算工具的培训。重点是开发有力的机械基础知识及其在行业驱动工程发展方面的应用专家。培训的跨学科性质得到了国际和国家合作的补充。该策略旨在以合理的批判性判断力和灵活的技能来发展独立的工程师。该计划对加拿大的潜在好处是：行业竞争力和较低的温室气体排放（例如，飞机发动机和风力涡轮机的改善）；缓解风暴；新技术和高素质人员的高级培训。