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

在本研究中，大尺度湍流，速度剪切和浮力对相干结构加热射流的影响进行了实验研究。采用主动网格湍流剪切流发生器模拟了大尺度湍流场。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，加热射流在远离射流出口处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，加热射流在风洞中出现了弯曲运动。(2)在单股热射流情况下，浮力对射流内部的涡结构和势核有影响。(3)在浮力射流中几乎没有观察到稳定的涡对和稳定的大涡出现。浮力射流比未加热的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