The study of flow pattern in the flow boiling process holds great significance for the safety and automation production in nuclear, aerospace and other industries. A numerical simulation study on flow patterns for water boiling in horizontal heated tubes was conducted by volume of fluid (VOF) multiphase flow model and LEE evaporation-condensation model. And the effect of heat flux on the flow pattern evolution was analyzed. Four boiling flow patterns was obtained in the tubes, namely bubble, slug, annular, and stratified flows. The increment of heat flux pushes the starting point of each flow pattern toward the inlet of the tube, which gradually compresses the range of bubble and slug flow and expands the region of stratified flow. Due to the formation of stratified flow, the tube metal in the upper part is at high temperature, resulting in tube failure.
Keywords horizontal heated tube, boiling two-phase flow, VOF, flow pattern