A revised cavitation model for cryogenic cavitating flow computations

Abstract

The inducer operates in cryogenic liquids which have a lower liquid to vapor density ratio, significantly higher slopes of pressure-temperature saturation curve and other quantities such as latent heat and thermal conductivity, resulting in substantial thermal effects and strong variations in fluid properties. The goal of our overall efforts is to establish a predictive tool for cryogenic cavitating flows, especially the transport-based cavitation model. Specifically, a Rayleigh-Plesset Based transport model is presented which considered the thermal effect. A Revised cavitation model is introduced and the computational results of the Revised cavitation model is compared against the previous Kubota cavitation model under cryogenic conditions. Compared with the results of Kubota model, the reduced magnitude of the cavity length is larger for the Revised model and it can simulate the observed "frosty" appearance within the cavity better. The maximum temperature and pressure depressions for the cases show lower and the pressure returns to the free-stream pressure faster for the Revised model. The Revised model can capture the temperature and pressure depressions more exactly in the cavity region, especially at the rear end of the cavity, since the intensity of the evaporation and condensation show large distinction for the previous and the Revised models. The evaporation intensity is lowered, while the magnitude of the condensation term is stronger for the Revised model due to the thermal effect term. As evaporation occurs, the revised term of the evaporation rate is negative which will suppress the evaporation intensity. With increasing the cavitation intensity, the revised term of the evaporation rate become higher. For the condensation term, the revised term of the condensation rate is positive as condensation occurs which will enhance the condensation intensity. It also can be found that the revised term of the condensation rate is higher when the condensation intensity is larger. The Revised model is more sensitive to the thermal effect of cavitation. The effectiveness of the Revised model is confirmed by using experimental data in cryogenic cavitation.