Simple and rational numerical method of two-phase flow with volume- junction model. 1. Verification calculation in saturated condition

摘要

A new numerical method to achieve a rigorous numerical calculation of each phase using a simple explicit method with volume-junction model is proposed. For this purpose, difference equations for numerical use are carefully derived so as to preserve the physical meaning of the basic equations. Specifically, momentum equations for the flow in the volume are newly derived to keep strict conservation of energy within the volume. To prove the validity of the numerical method and of previously proposed basic equations, including the original phase change equations, which were rigorously derived, some numerical calculations were made for each phase independently to examine the correctness of calculated results. The numerical calculation is advanced by simple integration of an explicitly obtained solution of difference equations without any special treatment. Calculated results of density and specific internal energy of each phase for saturated two-phase blowdown behavior are consistent for two different solution scheme as described below. Further, no accumulation of error in mass or energy was found. These results prove the consistency among basic equations, including phase change equations, and the correctness of numerical calculation method. The two different solution schemes used were: (1) solutions of pressure and void fraction in saturated condition were obtained by using mass conservation equation of each phase simultaneously, and (2) fluid properties were calculated directly from mass and energy conservation equation of each phase. (author)