论文标题
大涡模拟的湍流分离和重新连接的环形流中的流量
Large-eddy simulation of turbulent separated and reattached flow in enlarged annular pipe
论文作者
论文摘要
这项研究对湍流的分离和重新触及的环形流中的湍流进行了大型模拟。涡流环从突然的膨胀部分定期脱落。在涡流环附近发生纵向涡流，使流量三维。结果，涡流环变成不稳定的下游并将其分成小涡流。管状纵向涡流结构发生在内管侧壁表面附近的重新介绍点的下游。在每个管道直径比下发生低频波动。管道直径比的越小，小尺度涡流的影响就越下游，并且出现了对流场的低频波动。管道直径比的越小，从重新进程点下游的压力回收速度越慢。与外管侧相比，内管侧的压力回收延迟。湍流是由于涡旋环的崩溃产生的小尺度涡流而导致的重置点的最大上游。随着管道直径比下降，该最大值降低。管道直径比越小，从重新计算点下游的湍流越高。
This study performs a large-eddy simulation of turbulent separated and reattached flow in an enlarged annular pipe. A vortex ring is periodically shed from the sudden expansion part. A longitudinal vortex occurs around the vortex ring, making the flow three-dimensional. As a result, the vortex ring becomes unstable downstream and splits into small vortices. A tubular longitudinal vortex structure occurs downstream of the reattachment point near the wall surface on the inner pipe side. A low-frequency fluctuation occurs at each pipe diameter ratio. The smaller the pipe diameter ratio is, the more downstream the influences of small-scale vortices and low-frequency fluctuation on the flow field appear. The smaller the pipe diameter ratio, the slower the pressure recovery downstream from the reattachment point. The pressure recovery on the inner pipe side is delayed compared to the outer pipe side. Turbulence is maximum upstream of the reattachment point due to the small-scale vortices generated by the collapse of the vortex ring. This maximum value decreases as the pipe diameter ratio decreases. The smaller the pipe diameter ratio, the higher the turbulence downstream from the reattachment point.
