Hydrodynamics of Vortical Gas Jets Coupled to Point-Like Suction.
Hydrodynamics of Vortical Gas Jets Coupled to Point-Like Suction.
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DOI：
10.1063/5.0019840
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发表时间：
2020-10
影响因子：
4.6
通讯作者：
Jung Y. Lee;P. Kottke;A. Fedorov
中科院分区：
文献类型：
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作者：
Jung Y. Lee;P. Kottke;A. Fedorov
采用光学可视化技术对雷诺数Re为1000 ~ 3425、旋流数S小于0.5的旋涡射流流场进行了实验研究。纹影摄影是用来评估涡流结构，并建立源汇气体动力学耦合的基本理解，包括流量，射流直径，气体射流源和吸汇之间的分离距离所发挥的作用。与无涡射流相比，Re>2700且旋流数S>0.27的旋涡射流经历了更早的层流到湍流的转变，从而导致射流边界的快速增长。通过使用同轴对齐的流抽吸放置在射流的路径中，证明了控制射流膨胀的增长以及质量和动量耗散到周围的能力。当旋转射流与流动抽吸完全耦合时，射流膨胀被显著抑制。吸入/下沉流率对气体射流的最大输入/源流率施加限制以实现完全耦合。此外，有一个最大的距离，有效的耦合可以发生，并为所有的雷诺数考虑，这个距离是短于距离的射流结构分裂成湍流漩涡在没有一个汇。
Vortical jet flows in the Reynolds number (Re) range from 1000 to 3425 and swirl number (S) below 0.5, alone and in combination with suction through a small aperture, are experimentally investigated using optical visualization. Schlieren photography is employed to assess the vortical flow structure and establish the fundamental understanding of the source-to-sink gas-dynamic coupling, including the role played by flow rate, jet diameter, and the separation distance between the gas jet source and the suction sink. Compared to vortex-free jets, vortical jets for Re>2700 with swirl number S>0.27 experience earlier laminar-to-turbulent transition, with resulting rapid growth of the jet boundary. The ability to control growth of the jet expansion and mass and momentum dissipation into the surrounding is demonstrated via use of a coaxially aligned flow suction placed in the path of a jet. When a swirling jet is completely coupled with a flow suction, jet expansion is significantly suppressed. The suction/sink flow rate imposes a limit on the maximum input/source flow rate of gas jet to achieve complete coupling. Furthermore, there is a maximum distance over which effective coupling can occur, and for all Reynolds numbers considered this distance is shorter than the distance at which the jet structure breaks up into turbulent eddies in the absence of a sink.