弯管内三维湍流场的实验研究

Experimental study of 3-dimensional turbulent flow field in a bend pipe

采用激光多普勒测速仪(简称LDV)对U型弯管流场进行了测量,得到切向速度与轴向速度的分布。进而证明了流体在弯管内流动受弯管壁的限制,被强制沿弯管作适体的圆周运动而产生惯性离心力,表现出压力不均匀分布流体的速度。轴向速度的存在也证明了在U型弯管湍流流场中,存在着较为强烈的二次流。

Flow field in the U-shaped bend is measured by using laser Doppler velocimetry （LDV）. Distribution of tangential ve- locity and axial velocity are introduced particularly, which definitely represent that fluid in the bend are restricted by the elbow bend wall and has to be forced to make circular motion. This circling motion produces the inertial centrifugal force and the uniform distribu- tion of the velocities. It is proved that there are strong secondary flows based on the existence of the axial velocity in the turbulent flow in the U-shaped bend.