Direct numerical simulation of turbulent flow of liquid hydrogen with wall boiling

The flow of a cryogenic fluid such as liquid hydrogen can become turbulent, and phase changes can occur owing to variations in wall temperatures, resulting in significant alterations in the flow field. Direct numerical simulations were conducted to investigate turbulent liquid hydrogen with near-wall boiling in a parallel-plate channel. The simulations showed that heating one wall induced boiling within fully developed wall turbulence. The turbulence statistics and the relationship between near-wall turbulence structures and phase change were analyzed in detail. The results demonstrate that boiling phenomena accelerate wall-normal and spanwise velocities that promote the sweep and ejection near the wall, temporarily increasing the turbulent kinetic energy by approximately 1.5 times. Additionally, turbulence influences boiling after an initial transient period, thereby enhancing phase-change. The turbulence statistics indicate that boiling modulates wall turbulence toward isotropy. The local phase change also increases the streamwise velocity near the wall, which in turn reduces the velocity gradient, thereby decreasing the turbulent kinetic energy. Furthermore, the combined effects of these mechanisms reveal a turbulence modulation due to the interaction between the near-wall turbulence structure and the phase change, characterized by turbulence enhancement, followed by its suppression over time. Accurately predicting these phenomena using statistical modeling techniques that treat the turbulence structure as the Reynolds stress is fundamentally challenging, and an appropriate turbulence model is required to reproduce the phenomena observed in this study. • Direct numerical simulation and phase change model of liquid-hydrogen turbulent flow. • Relationship between the turbulence structure and phase change investigated. • Boiling phenomena increase and decrease the turbulent kinetic energy and vortices. • Turbulence promotes a phase change from the wall. • Acceleration of flow near the wall induced by boiling affects the turbulence modulation.