环空流道液流失速水击特性及其成因的研究

Study of the Flow Stall Water Hammer Characteristics in an Annulus Flow Channel

环空流道与圆管的结构差异,使得其失速水击特性及其成因亦有不同。为了对其进行分析研究,利用PIV对套管环空和圆管流水击流场进行拍摄,并通过Tecplot显示流场,提取轴向速度和径向速度、等速度线等参数加以分析;同时采用高精度智能动态压力传感器采集了套管环空内、外壁及内管内壁压力,对环空中水击特性进行了进一步研究。结论是:水击发生时环空断面外壁面水击压力大于内壁面水击压力;同初速情况下环空液流水击压力大于圆管流水击压力;环空中水击压力衰减速度快于圆管中;涡流是水击压力衰减以及速度变化的主要因素;水击压力振荡变化主要是压力涡流引起的断面能量的相互转化形成的。

The flow stall water hammer characteristics and its cause between annulus flow channel and circular tube are different due to their structure difference.In order to analyze this phenomenon,the water hammer fields of both annulus flow channel and circular tube were recorded by using PIV photographing,and the flow fields were visualized by using Tecplot.Axial velocity,radial velocity,isovelocity line and other parameters were extracted and analyzed.At the same time,further study of the water hammer characteristics of annulus flow channel were carried out by using high accuracy intelligent dynamic pressure sensor mounted on outer and inner walls inside the casing annulus.Results show that water hammer pressure on outside wall is greater than that on inside wall in annulus flow channel;water hammer pressure of annulus flow channel is greater than that of circular tube under the condition of same initial velocity;the water hammer pressure decaying speed of annulus flow channel is faster than that in circular tube flow;vortex is the main factors of water hammer pressure decay and speed change;water hammer pressure is oscillated mainly due to the section energy conversion caused by vortex.