Numerical investigation of unsteady flow dynamics and bubble-vortex interactions induced by cavitation in a cryogenic liquid oxygen pump

The reliable and stable operation of liquid rocket engines depends critically on the performance of cryogenic liquid oxygen centrifugal pumps, where cavitation-induced flow instabilities can significantly impact efficiency and safety. This study employs Delayed Detached Eddy Simulation combined with structured grids to investigate the unsteady fluid dynamics in these pumps, with a particular focus on the influence of thermal effects on cavitation flow behavior. The results demonstrate that at lower cavitation numbers, significant pressure drops and large vortex formations lead to head loss, while higher cavitation numbers result in smoother flow and more uniform pressure distributions. Energy dissipation is primarily driven by the growth and collapse of vapor bubbles, vortex formation, and recirculation, with entropy generation shifting from the leading to the trailing edge of the impeller as cavitation intensity decreases. Notably, the compression-expansion term in the vorticity transport equation plays a critical role in amplifying vortex stretching and turbulence, driven by rapid density fluctuations due to bubble dynamics. The interaction between bubbles and vortices highlights the nonlinear nature of cavitating flows, influencing both vorticity transport and energy dissipation. These results emphasize the importance of understanding cavitation-induced flow instabilities and their impact on the internal dynamics of cryogenic liquid oxygen pumps, which is crucial for improving the operational performance of liquid rocket engines. Future work will focus on further blade design optimization and incorporating fluid-structure interaction models to improve cavitation resistance and overall pump performance.