Two-phase flow pattern in small diameter tubes with the presence of horizontal return bend

摘要: This study provides a qualitatively visual observation of the two-phase flow patterns for air-water mixtures inside 6.9, 4.95, and 3 mm smooth diameter tubes with presence horizontal return bend. The influence bend on are investigated. For D=6.9 at mass flux 50 kg m−2 s−1 having quality less than 0.1, no is seen larger curvature ratio 7.1. However, were reduced to 3, pattern in recovery region temporarily turned from stratified into annular flow. temporary transition phenomenon not so pronounced decrease tube diameter. It likely that this related surface tension reduction developing length swirl Based present visualization, three maps proposed describe effect pattern.