Numerical simulation for ice crystal formation in high-pressure supersonic humid air low-temperature flow

Icing in the valve port is a critical issue affecting the aerodynamic performance and operational safety of high-pressure air pressure reduction valve (HPAPRV). The high-pressure air throttling expansion process involves extreme experimental conditions such as high pressure, supersonic , ultra-low temperature, trace water, and confined environments, which make it difficult to observe the behavior of vapor icing in HPAPRV. Giving that the above issue, an icing computational model is developed to describe the formation and growth of ice crystals and predict the temporal and spatial variability of ice crystals in high pressure supersonic low-temperature flow. The model is verified by comparing calculated icing amount in the valve spool top with experimental data. The aerodynamic performance changes, the characteristics of ice crystal growth, the spatial distribution of ice crystals within the valve port channel are analyzed and discussed in detail. The results show that the high-speed expansion of the gas is accompanied by complex heat transfer, the gas temperature drops rapidly from 300 K to 95.44 K, the supersaturation of the vapor reaches quickly 125.96, and a large number of condensate nuclei are generated in the valve port, which then form ice crystals. Under the influence of the high-speed airflow, part of the ice crystals are concentrated in the vortex region, which gradually becomes frosted near the wall, and another part of the ice crystals are expelled with the airflow. The results can further deepen the understanding of icing behaviors in high-pressure, high-speed gas flow fields within confined spaces, thus being conducive to building anti-ice blocking control strategy in the PRV valve port.