AUTHOR=Gao Jinchen , Yue Yanwei , Meng Zhaoming , Li Xiaoyu , Shen Geyu 

TITLE=Influence of the Size and the Angle of Branches Connected to the Main Horizontal Pipe on the Onset of Gas Entrainment

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 8 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2020.00008

DOI=10.3389/fenrg.2020.00008

ISSN=2296-598X

ABSTRACT=The influence of the size and the angle of the branch on the onset of gas entrainment is explored in the present study. Since the previous studies were performed on small-sized branches, and the angles of the branches were specific (0° or -90°), it is difficult to apply them to arbitrary-angled branches. So, we conducted a series of experiments in a different direction of -30°, -45°, -60°, and -90° angles with the main pipe of 80 mm in diameter and a branch of 31 mm in diameter (T-tube). A new correlation is developed and can predict the most experimental data well within the error range of ±20%. And the new correlation can predict the onset of gas entrainment at arbitrary-angled branch, and is not constrained by the angle of branches, that is, has good versatility. We also gained some meaningful conclusions by analyzing experimental data and the entrainment phenomenon: gas is entrained by a vortex flow, and the size of the branch and the angle of the branch have little effect on the form of entrainment at a given h_b/d; The critical Froude number ({Fr}_L) gradually increases as the angle of the branch changes from -90° to -30°; By comparing with previous models, it can be found that the correlation of onset of gas entrainment based on small-sized branches is not suitable for large-scale branches. But we have defined a new critical liquid level (hb*) to successfully expand the scope of application of correlation.