Multidimensional simulation of thermal nonequilibrium flows in a convergent-divergent nozzle

The aim of this effort is to employ the homogeneous relaxation model to study thermal nonequilibrium in flash boiling flows. The use of convergent-divergent nozzles is prevalent in geothermal total flow systems for power generation, and the understanding of the physics of two-phase flows in such systems is of primary importance to achieve greater efficiencies. Most numerical studies for such nonequilibrium phase-change models have used one dimensional approaches, but the objective of the present work is to utilize a multidimensional computational fluid dynamics implementation for such complex flows. It was observed that the slip between the vapor and liquid along the divergent section of the nozzle and the maximum nonequilibrium pressure drop at the nozzle throat due to the thermal nonequilibrium causes an increase in the nozzle efficiency with the decrease in back pressure. The model was validated against experimental measurements and it was observed that the simulations are in good agreement with the multidimensional features observed in the experiments. © 2019 by Begell House, Inc