Properties of a Critical Two-Phase Flow through a Granular Bed

The paper presents the results of a theoretical study on velocity of a vapor-liquid flow and velocities of its constituent vapor and liquid phases under a critical flow through a granular bed. The focus is made on a model of isenthalpic flow with a phase slip, where the vapor-liquid flow expansion is defined by polytropic equation. The polytropic coefficient and slip ratio are determined based on the results of the previous experiments with the particles of 2 mm and 4 mm in diameter and a bed height of 50-355 mm. The study demonstrates the impact of pressure and flow quality at the bed inlet and a ratio of particle diameter to bed height on the inlet and outlet velocities of the mixture, its vapor and liquid components under critical conditions. An empirical dependence is proposed to find the critical pressure ratio in the bed. The generalizing laws for critical inlet and outlet Mach numbers are revealed.