横向气流作用的水平管降膜厚度分布研究

Study on the Horizontal Tube Falling-Film Thickness Under Cross Airflow

液膜厚度是反映水平管外液膜流动特性的重要参数之一。本文采用空气–水体系和电导探针法实验研究了管间柱状流条件下轴向和周向液膜厚度分布,分析了横向气流对液膜厚度分布的影响机理。结果表明,无气流作用时,波峰处周向液膜厚度随周向角增大先减小后增大,最小值在100°~120°区间,相邻波峰间轴向液膜厚度先增大后减少;横向气流作用时,迎风面液膜厚度在周向角30°~90°内增大、90°~150°内减小,背风面液膜厚度增大,而轴向迎风面液膜厚度波峰范围和铺展面积增加,背风面变化不显著。

The liquid film thickness distribution is one of the most important parameters to charac-terize the flow characteristics outside the horizontal tube.The axial and circumferential film thickness distributions under column fow mode are measured using the air-water system and the conductance probe method,and the effect of the cross airflow is analyzed.The results show that the circumfer-ential film thickness at the wave crest decreases and then increases with increasing circumferential angle,and a minimum value occurs within the circumferential angle of 100°~120°.The axial film thickness has a wave crest region and is symmetric distributed in the quiescent surroundings.When the cross airflow exists,the circumferential film thickness on the windward surface increases in the circumferential angle of 30°~90°and decreases in the circumferential angle of 90°~150°,while those on the leeward surface becomes more uniform.The axial wave crest region and spreading region of the liquid film on the windward surface also increase,but those on the leeward surface change little.