Exhaustion of a Steam Liquid Flow through a Channel with a Monodispersed Grain Layer

The authors performed 3D numerical simulation of the unsteady outflow of a two-phase liquid-vapor flow from a tube with spherical monodisperse filling. The numerical model was developed by the smoothed particle method, and its verification was carried out using experimental data on the motion of a bubble flow in a tube. The minimum size of smoothed particles and their required number to build a correct computational model have been determined. Structural and hydraulic characteristics of the flow in the presence of phase transitions have been obtained. The calculated data on the three-dimensional spatial distribution of the vapor phase and pressure losses both over the cross section of the unit cell formed by the dispersed backfill and along the entire length of the channel are given. The analysis of the dynamics of changes in pressure losses along the length of the tube has been carried out; two characteristic sections with different dynamics of the growth of pressure losses have been found. Data were obtained on the distribution of the volumetric steam content in the tube at its various positions: horizontal, vertical, and with an inclination of 45 degrees. The influence of the angle of inclination of the tube on the character of the distribution of steam over its cross section is shown. In this case, the greatest difference in the structure is observed between the vertical and horizontal positions. It has also been demonstrated that its structure tends to be homogeneous as the flow moves. The calculation model used made it possible to determine pressure loss in the working section from the inlet of the vapor-liquid flow into the tube to the outlet under conditions corresponding to the onset of the critical flow regime. Comparison of the results of numerical calculations, including the critical mass flow rates at the outflow of a vapor-liquid flow from the tube, with the available experimental data and previously obtained results of analytical studies, noted their good match.