Two-phase pressure drop in a horizontal thin annulus: Effects of channel vibration and wall gas injection

Two-phase pressure drop in a narrow horizontal annular test section was experimentally investigated, using air and water as the working fluids. The annular test section had inner and outer diameters of 7.93 mm and 9.53 mm, respectively. In one group of tests (constant quality tests) air and water were mixed before entering the test section. In another group (variable quality tests), gas was injected into the test section via the porous inner test section wall. The liquid Reynolds number varied in the ReL = 50–9000 range, and the test section exit qualities covered the 0–25% range. The measured total pressure drops were compared with the predictions of a one-dimensional model with several two-phase frictional pressure drop correlations. The pressure variations caused by flow acceleration were calculated based on the homogeneous flow assumption. The correlation of Beattie and Whalley [D.R.H. Beattie, P.B. Whalley, A simplified two-phase frictional pressure drop prediction method, Int. J. Multiphase Flow 18 (1982) 83–87] agreed reasonably well with results of both groups of tests.