温度压力对黏性流体中孔口气泡生成的影响

Effects of temperature and pressure on bubble formation in viscous liquids

温度压力对孔口气泡生成过程具有重要影响。以氮气-硅油气液体系为对象,在自行设计加工的高温高压可视化鼓泡塔中,采用高速摄像法,观察了单孔气体进料时孔口气泡的形成过程,测定了气泡直径与纵横比,考察了孔口气速(0~1000 cm·s^-1)、温度(283~473K)、压力(0~3 MPa)以及孔径(1.12和2.5 mm)对气泡生长过程的影响。实验表明,黏性液体中呈现出大小气泡成对产生的双气泡生成模式;气泡直径随温度和压力升高而减小;低温时压力对气泡直径影响较小,高温时影响显著。通过与以往气泡直径关联式进行对比,修正了GADDIS提出的气泡直径模型,得出新的适用于高温高压条件下气泡直径的估算式。

Temperature and pressure are important factors affecting bubble formation on submerged orifices.Bubble formation processes were observed through a single orifice and recorded by a high speed camera in a home-designed visual bubble column under high temperature and pressure,and bubble diameters and bubble aspect ratios were measured.The experimental conditions were:orifice velocity 0~1000cm·s^-1,temperature 283~473K,pressure 0~3 MPa and orifice diameter 1.12 and 2.5 mm.The results show that bubbles of big-small pairs are the main forms in viscous liquid.Bubble diameter decreases with increase of pressure and temperature.The effect of pressure on bubble diameter is not obvious at lower temperature but evident at higher temperature.By comparing with previous correlations,a new correlation based on Gaddis’s model is developed to predict the bubble detachment diameter,which is applicable for high temperature and pressure conditions.