Experimental Examination of Gas-liquid Two-phase Flow Patterns in an Inclined Rectangular Channel with 90° Bend for Various Vertical Lengths

In order to realize the behavior of two-phase flow in an inclined rectangular channel with 90̊bend for various vertical lengths, an experimental investigation has performed. The test section (a chanel with 30 m length) contains two horizontal parts and a middle vertical section. Three vertical lengths of 50, 100 and 150 cm were utilized along the test section. The cross section of the rectangular channel is 10 cm × 15 cm. Air and water were the fluids used in this work. Various flow patterns are created by varying the volumetric flow-rates of gas and liquid; the air and water flow rates were in the range of 2 to 10 𝑚³ℎ⁄ and 34 to 235𝑚³ℎ⁄, respectively. The high speed video system was utilized to achieve image subsequence of the flow under various conditions. The effects of vertical length on flow regimes and pattern transition borders are examined. According to the flow visualization, no vortex was observed in the vertical section. The significant flow regime in the vertical section is churn flow regime. It is concluded that the flow pattern structures are not greatly affected by changing the vertical length.