Investigation of Asymmetric Free and Confined Three-dimensional Turbulent Jets using Time-Resolved Tomographic Particle Image Velocimetry

使用时间分辨断层粒子图像测速研究不对称自由和受限三维湍流射流

• 批准号: RGPIN-2017-04957
• 负责人: Tachie, Mark
• 金额: $ 3.21万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=666373
• 关键词: Investigation; Asymmetric; Free; Confined; Three

A novel numerical and experimental research program is proposed to investigate the mixing and turbulence characteristics of free jets, and jets that are offset from a solid wall or free surface. These jets occur in many engineering applications. The main goal of the research is to provide scientific understanding of turbulence mixing in these jets and create a repository of high-quality databases that will enable the research community to develop reliable predictive tools for turbulent jets. The short-term objectives, which will be achieved over the next 5 years, are to understand how changes in nozzle geometry affects turbulence characteristics of free jets, and to evaluate the effects of offset distance of a jet from a rigid wall or free surface on turbulent transport phenomena. Over this 5-year cycle, 16 HQP (5 PhD, 1 MSc and 10 BSc) will be trained to perform novel experiments and numerical simulations that will enable them to develop a thorough understanding of turbulent jets. They will develop skills that will prepare them for employment in academia or diverse industries of socio-economic importance to Canada.***The jets will be produced from nozzles with round, rectangular and elliptical cross sections, and will be offset at different distances from a wall or free surface. A world-class time resolved tomographic particle image velocimetry system (TR-Tomo-PIV) will be used to perform instantaneous and simultaneous measurements of all three velocity components in three-dimensional domain (3C-3D) on a magnitude that has never before been achieved in the experimental study of turbulent jets adjacent to a wall or free surface. The TR-Tomo-PIV is the latest evolution of PIV, a technique that has revolutionized the experimental study of turbulent flows. The 3C-3D databases will be used to calculate all the mean velocities and higher turbulence statistics, and to perform proper orthogonal decomposition of the proposed turbulent jets. The decay and spread rates will be evaluated to assess how changes in nozzle geometry or offset distance from a boundary affect the mixing characteristics of turbulent jets. ***The jets identified in this proposal are more complex than the canonical shear flows being simulated in the turbulence modelling community, and will represent acute test cases for numerical models. The experimental results will also facilitate the development of more effective second-moment closures, which too often have not been validated against full field measurements. These new models will enable the engineering community to reduce its reliance on physical model testing and design high performance fluid systems. The improved understanding acquired from this research and the new numerical models will lead to the development of innovative technologies and design of energy efficient and environmentally-friendly engineering systems in the aerospace, HVAC and power generation industries.**

提出了一种新的数值和实验研究计划，以研究自由射流的混合和湍流特性，以及射流偏离固体壁面或自由表面。这些射流出现在许多工程应用中。该研究的主要目标是提供对这些射流中湍流混合的科学理解，并创建一个高质量数据库库，使研究界能够为湍流射流开发可靠的预测工具。短期目标，这将在未来5年内实现，是了解喷嘴几何形状的变化如何影响自由射流的湍流特性，并评估射流从刚性壁或自由表面的偏移距离对湍流传输现象的影响。在这个为期5年的周期中，16名HQP（5名博士、1名硕士和10名理学学士）将接受培训，以进行新颖的实验和数值模拟，使他们能够深入了解湍流射流。他们将培养技能，为他们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做好准备。射流将从具有圆形、矩形和椭圆形横截面的喷嘴产生，并且将在距壁或自由表面不同的距离处偏移。一个世界级的时间分辨层析成像粒子图像测速系统（TR-Tomo-PIV）将被用来执行瞬时和同时测量的所有三个速度分量在三维域（3C-3D）的幅度，以前从未实现在实验研究中的湍流射流相邻的墙壁或自由表面。TR-Tomo-PIV是PIV技术的最新发展，是一种彻底改变湍流实验研究的技术。3C-3D数据库将用于计算所有平均速度和更高的湍流统计数据，并对拟议的湍流射流进行适当的正交分解。将评估衰减和扩散率，以评估喷嘴几何形状或与边界的偏移距离的变化如何影响湍流射流的混合特性。*** 本提案中确定的射流比湍流建模社区中模拟的规范剪切流更复杂，并将代表数值模型的急性测试用例。实验结果还将促进更有效的二阶矩闭合的发展，这往往没有得到验证，对全面的现场测量。这些新模型将使工程界能够减少对物理模型测试的依赖，并设计高性能流体系统。从这项研究中获得的更好的理解和新的数值模型将导致创新技术的开发和航空航天，HVAC和发电行业节能环保工程系统的设计。