Thermal stratification and fluid oscillation induced by steam–air mixture horizontal jets

Abstract

• Sparger intensifies thermal stratification. • Long pipe weakens thermal stratification. • Fluid oscillation amplitude increased with pipe length. An experimental study was conducted on trigger conditions of thermal stratification (TS) and fluid oscillation (FO) parameters during steam–air mixture horizontal jets at low mass flux. Two pipes with different lengths and a sparger were used as nozzle. Temperature distributions in the pool and nozzle were monitored continuously through thermocouples. In the experiments through pipe, only slight TS was observed in the case of short pipe. In the experiments through sparger, TS was observed in all pure steam jets and steam–air mixture jets with air mass fraction below 2%. Comparison between present experiments and previous experiments of vertical jets showed that horizontal jets were less prone to TS under the same conditions. Compared with short pipe, the experiments through long pipe had larger FO amplitude. The experiments through sparger had smaller probability and amplitude while larger frequency.