Influence of convective heat transfer modeling on the estimation of thermal effects in cryogenic cavitating flows

摘要

The accuracy of numerical simulations for the prediction of cavitation in cryogenic fluids is of critical importance for the efficient design and performance of turbopumps in rocket propulsion systems. One of the main remaining challenges is efficiency in modeling of the physics, handling the multi-scale prop erties involved and developing robust numerical methodologies. Such flows involve thermodynamic phase transitions and cavitation bubbles that are on a smaller scale than the global flow structure. Cryo genic fluids are thermo-sensitive, and therefore, thermal effects and strong variations in fluid properties can alter the cavitation properties. The aim of this work is to address the challenge posed by thermal effects. The Rayleigh-Plesset equation is modified by the addition of a term for convective heat transfer at the interface between the liquid and the bubble coupled with a bubbly flow model to assess the pre diction of thermal effects. We perform a parametric study by considering several values of and models for the convective heat transfer coefficient, h_b, and we compare the resulting temperature and pressure pro files with the experimental data. Finally, the results of a 2D simulation with a commercial CFD code are presented and compared with the previous results. We note the importance of the choice of h_b for the correct prediction of the temperature drop in the cavitating region, and we assess the most efficient mod els, underlining that the choice of h_b estimation model in a cryogenic cavitating flow is more important in the bubble growth phase than in the bubble collapse phase.