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

在加热射流中，实验研究了大尺度湍流、速度剪切和浮力对相干结构的影响。采用带有源网格的湍流切变流发生器产生大尺度湍流场。分别用烟丝法和热风速仪对速度场和温度场进行了可视化和测量。(1)在大尺度湍流场中远离射流出口的远区，加热射流受到大尺度湍流涡的影响。加热射流的温度波动是间歇性的，加热射流在风洞内发生了弯曲运动。(2)在单加热射流的情况下，浮力对射流内部涡结构和势核的行为有影响。(3)在浮力射流中几乎没有观测到稳定涡对和大涡的稳定发生。浮力射流比非加热射流从更上游变得湍流

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