基于高频响Tomo-PIV的脉冲旋转射流涡动力学与掺混强化实验研究

脉冲旋转射流既能通过涡环的卷吸效应强化射流在近喷嘴附近的掺混性能，同时又能促进旋涡结构的破灭提高远喷嘴区域的掺混能力。值得指出的是，旋转涡环之间以及涡环与二次涡和大尺度模态结构之间的非线性干扰促使流场产生更为复杂的动态特性，对强化掺混将起到非常重要的作用。本项目将对脉冲旋转射流形成的涡环序列开展高频响全三维的Tomo-PIV流场测量和PIV/PLIF的流场标量场同步测量工作。首先通过众多组合参数的平面PIV测量来量化参数对流场特性的影响规律；随后针对典型参数下的Tomo-PIV测量结果，分析流场的三维结构特征和动态演化特性；最后，使用平面PIV/PLIF同步测量结果，结合Tomo-PIV全三维流场数据，深入研究标量场的调制机制以及脉冲旋转射流强化掺混机理。本项目的相关研究成果将揭示脉冲旋转射流涡动力学演变机制及其对流动掺混的影响规律，对射流的强化掺混控制策略的制定提供理论支撑。

The pulsed swirling jet induces the vortex rings which enhance the near-nozzle mixing by the strong entrainment effect and speeds-up the vortex breakdown which increases the mixing rate in the far-nozzle regions. It is also worth noting that the non-linear interactions between the vortex rings, and that between the vortex ring and the secondary vortical and large-scale modal structures, induce more complex dynamic characteristics in the flow and plays important roles in the mixing enhancement. The present study performs time-resolved fully three-dimensional Tomo-PIV flow field measurements and simultaneous Planar-PIV/PLIF flow and scalar fields measurements for the swirling vortex rings generated by the pulsed swirling jet. Firstly, the Planar-PIV results are used to quantify the effects of the pulse and swirling parameters on the flow structures and characteristics; secondly, the Tomo-PIV results are employed to characterize the three dimensional structural characteristics and the dynamic evolution of the swirling vortex rings; lastly, the simultaneous Planar-PIV/PLIF measurement results, together with the Tomo-PIV data, are analyzed for the in-depth study of the mechanism of scalar field modulation and the mixing enhancement by pulsed swirling jet. The results of this study will reveal the evolution mechanism of vortex dynamics and the its influence on the flow mixing, and provide theoretical supports for the formulation of the control strategy.