【摘要】 为了研究气液逆向降膜蒸发式冷凝器管内液膜的稳定性，通过数值仿真模拟方法，获得了绝热条件下降膜蒸发式冷凝器竖直管内液膜的流动特性。结果表明：在管内自然通风和强制通风条件下，竖直管内降膜过程均可分为起始段、稳定段、起伏段、波动段4个阶段，逆向气流扰动会改变4部分在管内的分布位置与范围；稳定段液膜厚度取决于液体雷诺数，空气流动速度增加会增大波动程度并扩展波动段范围，当液体雷诺数为2 440～6 100时对应的临界气体雷诺数约为914～2 583，以临界气体雷诺数强制通风时相比无强制通风时液膜的波动段平均延长了11%，这表明逆向通风强度与液膜稳定性密切相关，在本文模型下液体雷诺数为4 880时液膜稳定性较好。研究结论对于竖直管内降膜蒸发冷凝换热器的设计和运行具有重要的指导意义和参考价值。更多还原

【Abstract】 In order to study the stability of the liquid film in the gas-liquid reverse falling film evaporative condenser tube，the flow characteristics of the liquid film in the vertical falling film evaporative condenser tube under adiabatic conditions were studied by numerical simulation method.The results show that under the conditions of natural ventilation and forced ventilation in the tube，the falling film process in the vertical tube can be divided into four sections：the initial section，the stable section，the undulating section，and the fluctuating section.The disturbance of the reverse airflow will change the distribution position and range of the four sections in the tube.The thickness of the liquid film of the stable section depends on the Reynolds number of the liquid.The increase of air flow speed will increase the degree of fluctuation and expand the range of fluctuations.When the liquid Reynolds number is 2 440～6 100，the critical gas Reynolds number ranges from 914 to 2 583.When the ventilation is at the critical Reynolds number，the fluctuation period of the liquid film is extended by an average of 11% compared with the case without forced ventilation，which means that the degree of reverse ventilation is closely related to the stability of the liquid film.In this model，the liquid film is relatively stable when the liquid Reynolds number is 4 880.The research conclusions have important guidance and reference value for the design and operation of the evaporative condenser based on the falling film in te vertical tube.更多还原