Abstract: Effects of inclination on radial distribution of interfacial parameters were investigated for air-water bubbly flow in a pipe with the diameter of 50 mm.The double optical fiber probe method was used for measuring the local parameters of void fraction,interfacial area concentration and bubble passing frequency.Air and water were used as working fluids,with the superficial velocities of 0.002—0.037 m·s^-1 and 0.072—0.569 m·s^-1,respectively.Three inclination angles of 5°,15° and 30° were selected for the experiments.Four classical distribution types of the core peak,wall peak,intermediate peak and transition appeared under vertical flow condition.While for the inclined condition,bubbles congregate toward the upper wall of the pipe,resulting in the asymmetrical distribution of these parameters.The central broad peak leaned to the upper part of the tube,with its peak value increasing as the inclination angle increased.In the meantime,the peak near the lower wall lowered gradually,even disappeared, while the other one near the upper wall escalated accordingly.The interfacial parameters increased diametrically from r_i/R=-0.84 to the peak location around the upper wall,with its variation rate increasing as the inclination angle increased.The Sauter mean diameter under inclined condition were larger than that of vertical flow.

Key words: double optical fiber probe, inclined pipe, bubbly flow, interfacial parameter distribution, buoyancy force

摘要： 采用双头光纤探针法研究了倾斜对圆管内(I.D.50 mm)上升泡状流界面参数径向分布的影响。探针测量的局部界面参数包括局部空泡份额、界面面积浓度(IAC)和局部气泡通过频率。实验以空气和水为工质,表观速度分别为0.002~0.037 m·s^-1和0.072~0.569 m·s^-1;倾斜角度为5°、15°和30°。结果表明,竖直条件下界面参数呈核峰型、壁峰型、中间型及过渡型4种典型的分布。倾斜条件下大量气泡向上部聚集,界面参数分布不对称。中间宽峰向通道上部倾斜,且峰值随倾斜角度增加而增大。同时,下壁面附近峰值被削弱,甚至消失,上壁面附近峰值迅速增大。界面参数沿直径从r_i/R=-0.84到上半部分峰值处逐渐增加,且增加速率随倾斜角度增加而增大。倾斜条件下Sauter直径明显比竖直条件下大。

关键词: 双头光纤探针, 倾斜管, 泡状流, 界面参数分布, 浮力