水平矩形管内气-液逆向流动特性实验研究

Experimental Study of Gas-Liquid Countercurrent Flow Characteristics in Horizontal Pipes with Rectangular Cross-section

为探明管截面尺度及排气水深对水平矩形管内气-液逆流特性的影响,以空气和水为两相介质,对管长2 m、管截面尺寸106 mm×60 mm的矩形管分别在横置、竖置条件下和1 、3 m水深下进行了可视化流动实验。结果表明:管截面高度尺度对气-液逆流特性具有显著影响,在相同的管道流通面积下采用较高的流道高度会大幅强化水平管内液相倒流,从而有利于冷凝水由热段顺利回流至堆芯进行冷却;采用管截面高度作为气相及液相Wallis参数中的特征尺寸,可使不同管截面尺寸矩形管的无量纲逆流特性获得统一表征;在水深1~3 m范围,水深变化对水平矩形管内气-液逆流特性的影响并不明显。提出了预测水平矩形管内气-液逆向流动特性的无量纲实验关联式。

To clarify the effects of the cross-sectional sizes and water depths on the gas-liquid countercurrent flow characteristics (CCFC)in horizontal rectangular pipes,a visualization CCFC experiment was carried out through an underwater exhaust experimental system using air and water as the gas and liquid phase.In the experiment,a rectangular plexiglass pipe in a length of 2 m and inner cross-section scale of 106×60mm was tested under the transversal and upright layout, respectively,and each layout was tested under the water depth of 1 m and 3 m.Conclusions can be drawn as follows:(1).The height of flow channel has a significant effect on the horizontal CCFC in pipes.The liquid phase backflow can be greatly enhanced if using a higher channel height under a given cross-sectional area of pipes,which is beneficial to condensate water reflux in hot legs thus ensuring the cooling of reactor cores under the loss of coolant accident.(2)The dimensionless CCFC curves of the transversal and upright layout,which curves are expressed by the Wallis parameters of the gas and liquid phase,were coincided when the channel height was used as the characteristic scale of Wallis parameters,meaning that the CCFC of the horizontal pipes in different cross-sectional sizes could be well correlated using such a definition of Wallis parameters.(3)The influence of changing water depth on the dimensionless CCFC in horizontal rectangular pipes is insignificant in the range of water depth 1-3 m.Finally,an experimental correlation was proposed for predicting the CCFC in horizontal rectangular pipes.