Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

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.