Abstract: Experimental investigation was carried out on the characteristics of void fraction distribution in a narrow rectangular duct (3.25 mm×43 mm) as well as a conventional circular tube (i.d.50 mm) under inclined conditions to study the influence of inclination on bubble and gas-liquid interface distribution. Air and purified water were used as the test fluids and three inclination angles of 5°, 10° and 15° were selected for experiments. Only wall peak distribution was observed in the narrow rectangular duct and no core peak was present, while for the circular tube, both were observed. Inclination had similar effect on wall peak distribution in two channels. Accordingly, with increasing inclination angle, the peak near the upper wall of the tube boosted up, whereas, the one near the lower wall weakened gradually, and even disappeared. As to core peak distribution in the circular tube, central broad peak leaned to the upper part of the tube, and its value increased as inclination angle increased. In addition, the position of wall peak in the narrow rectangular duct was closer to the channel center than that in the conventional circular tube.

Key words: gas-liquid flow, bubble, interface, inclined conditions, void fraction

摘要： 对窄矩形通道（3.25 mm×43 mm）和常规圆管（i.d.50 mm）内泡状流空泡份额分布特性进行了实验研究，探究倾斜对气泡和气液界面分布的影响。实验以空气和纯净水为工质，倾斜角度为5°、10°和15°。结果表明窄矩形通道内空泡份额主要呈壁峰型分布，未观察到核峰型分布；常规圆管内存在核峰型和壁峰型两种分布类型。倾斜对窄矩形通道和常规圆管内壁峰型分布影响相似，即随着倾斜角度的增加，靠近上壁面的峰值被加强，靠近下壁面的峰值被削弱直至消失。对于圆管内核峰型分布，倾斜导致中间宽峰向通道上部倾斜，且峰值随倾斜角度增加而增大。此外，竖直和倾斜条件下壁峰型分布的峰值较常规圆管更加接近通道中心位置。

关键词: 气液两相流, 气泡, 界面, 倾斜条件, 空泡份额