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Date of Publication:2019-01-01

Journal:化工学报

Volume:70

Issue:12

Page Number:4565-4574

ISSN No.:0438-1157

Abstract:To fully understand the drop-like flow phenomenon of the horizontal tube falling film, this paper uses water as the experimental fluid, and uses a high-speed high-definition camera to visualize the drop-shaped flow of the horizontal tube under different pipe spacings. The droplet flow in low Reynolds number Re≤200 and tube spacing s≤40 mm is observed. Based on the different flow characteristic, the droplet flow can be divided into accumulation droplet flow, incomplete droplet flow, pendant droplet flow, complete droplet flow and incomplete retracting droplet flow. According to the experimental results, the partition map of droplet flow is presented. The concept of separation length is proposed, and the effect of flow rate on separation length is discussed. The relationship between dropping site spacing and flow rate in droplet flow at low Reynolds number was studied. The results show that the flow pattern of droplet flow is influenced not only by flow rate but also by tube spacing. With the increase of tube spacing in Re≤120, the flow patterns between tubes are converted from accumulation droplet flow to incomplete droplet flow to pendant droplet flow, and to complete droplet flow. When 25 mm≤s≤40 mm, as the flow rate increases, the flow patterns are successively converted from incomplete droplet flow to pendant droplet flow, and to incomplete retracting droplet flow. The separation length increases linearly in two stages with the increase of Re. The growth rate in Re≤60 is smaller than it in 60<Re≤140. The correlation of separation length with Re is established in this paper. In addition, the dropping site spacing of droplet flow is investigated. The dropping site spacing decreases with the increase of flow rate in Re≤100, and remains stable in the range of 100<Re≤200. Meanwhile, the dropping site spacing of droplet flow with Re is established.

Note:新增回溯数据