三维弯管内分离流场的试验研究

EXPERIMEMNTAL INVESTIGATION FOR SEPARATED FLOW IN THREE-DIMENSIONAL BEND DUCT

通过热线测速系统对三维９０°弯管分离流场的气流特性进行了实验研究，通过对分离流场的测量及观察，给出了时均速度、脉动速度、雷诺应力的大小等数据。结果表明：在管道的中心线附近远离分离泡区域的紊流可以看作各向同性的；而分离泡与主流的过渡区域表现为强烈的各向异性；回流区的平均速度场分布与紊流度无关，回流的雷诺剪应力大小与当地平均速度无关，回流不是来自很远的下游。

The experimental investigation for turbulent separated flow in a 3-D 90°bend duct is reported.It is shown that,near the duct centre-lines,the turbulent flow can be ide-alized as local isotropy.The region between the separated bubble and the main region shows strong anisotropy.So the anisotropy of closure assumptions has to be taken into account in prediction methods.The Reynolds stress in the recirculation region is due to the turbulence structure,not the local mean velocity gradient.