[2K19-23] Two-Phase Flow and Phase Change 2

[2K20] CORRELATION OF INTERFACIAL FRICTION FOR COUNTER-CURRENT FLOW IN A VERTICAL PIPE

*Takayoshi Kusunoki¹, Yasunori Yamamoto¹, Michio Murase¹, Akio Tomiyama² (1. INSS, 2. Kobe University)

Keywords:Countercurrent flow limitation, vertical pipe, one-region computation, interfacial friction factor

We have been experimentally and analytically evaluated countercurrent flow limitation (CCFL) in the hot legs, the pressurizer surge line and the heat transfer tubes of a steam generator, and derived Wallis-type CCFL correlations for them. To generalize a prediction method for CCFL in vertical pipes, in this study, we did one-region computations for CCFL inside vertical pipes (CCFL-P) based on the annular flow model with several correlations for the interfacial friction factors and compared the computed results with air-water CCFL data. From the comparison, we selected the correlation proposed by Bharathan et al. (1978), which is a function of the void fraction. Then we obtained adjustment factors for the diameters of D = 18, 25.4, 31.8 and 50.8 mm by fitting the results computed with the correlation by Bharathan et al. (1978) to the air-water CCFL data and derived an adjustment function with the dimensionless diameter (D^*). The results showed that the interfacial friction factors should be large for a large diameter pipe. It is difficult, however, to evaluate effects of fluid properties on the interfacial friction factors due to lack of steam-water CCFL data.