【摘要】 对洗涤冷却管内垂直降膜的流动特性进行了研究,采用超声波多普勒测速仪,对气相影响下液膜的厚度和速度进行了无接触式的测量,实验液膜雷诺数为2.04×10~4,气相雷诺数范围0~6.83×10~4。结果表明:液膜在洗涤冷却管流动发展过程中明显存在中央液膜向两边铺展的现象,铺展规律受气相雷诺数及出口槽缝尺度影响显著。管内周向角8和16°处局部液膜波动较其余周向位置剧烈并有增厚的趋势,且气相雷诺数和槽缝宽度的增大均使这两处液膜增厚位置向后延迟,使得管内初始段膜厚变薄。此外,气相雷诺数增大加强气液两相间的剪切作用,整体上加剧了液膜波动幅度,液膜速度波动趋势更加显著。更多还原

【Abstract】 Flow characteristics of vertical falling film in scrubbing cooling tubes were studied. The thickness and velocity of liquid film with gas interference were measured touchless by ultrasonic Doppler velocimetry under Rel = 2.04×10~4 and Reg = 0~6.83×10~4. The results show that the central film in the tube spreads to both sides, which is influenced by Reg and slot width. Fluctuation of liquid film is more intense in positions with 8 and 16° circumferential angles, which also shows thicker films. The increase of Reg and slot width make the thickening positions move backwards, which leads to thinner films at the inlet of the tube. Moreover, the increase of Reg enhances the shear interaction between gas-liquid interphase and increases fluctuation of film thickness.更多还原