Experimental Investigation of Interaction Process between a buoyant jet and Large-Scale Turbulence

本文通过实验研究了加热射流中大尺度湍流、速度剪切和浮力对拟序结构的影响。大尺度湍流流场是由具有主动网格的湍流剪切流发生器产生的。分别用烟丝法和热风速仪进行了速度场和温度场的可视化和测量。(1)在大尺度湍流场中射流出口远区，加热射流受到大尺度湍流涡流的影响。(2)在单个加热射流的情况下，浮力对射流内部的涡旋结构和势核的行为有影响。(3)在浮力射流中，几乎没有观察到稳定的涡对和大涡的稳定出现。与不加热的射流相比，浮力射流从更上游的位置变得湍急。

In the present research, the effects of large-scale turbulence, velocity shear and buoyancy on coherent structures were experimentally investigated in a heated jet. Large-scale turbulent fields were generated by a turbulence shear flow generator with an active grid. How visualization and measurement of velocity and temperature fields were conducted by a smoke wire method and a thermal anemometer, respectively.(1) In the far region from a jet exit in a large-scale turbulence field, the heated jet was affected by the large-scale turbulent eddy. Temperature fluctuation in the heated jet was intermittent and the meandering motion of the heated jet occurred in the wind tunnel.(2) In the case of single heated jet, buoyancy force has an effect on the behavior of vortex structures and the potential core inside of the jet.(3) The stable vortex pairing and the steady occurrence of the large vortex were scarcely observed in the buoyant jet. The buoyant jet became turbulent from more upstream than the unheated jet