Application of multi-process cavitation model for cavitating flow in cold water and in liquid nitrogen around a hydrofoil

As one of the improvements of the conventional cavitation models, a new cavitation model named "Multi-Process Cavitation Model", which takes various elementary processes in cavitation such as bubble expansion/shrinkage with bubble-bubble interaction, evaporation/condensation, inception/collapse, coalescence and break-up into account, has been recently constructed. In this paper, we validated this cavitation model with a CFD solver around a hydrofoil of NACA0015 in cold water, together with the validation around a hydrofoil of NACA16-012 in liquid nitrogen as one of the cryogenic fluids. As a result, in the case of cold water, the prediction accuracy of the lift coefficient was improved compared with some typical conventional models. It was confirmed that one of the reasons why the present model improves the prediction accuracy of the lift coefficient is we take apparent "inception delay" into account based on the typical size distribution of pre-existing bubble nuclei. On the other hand, in the case of liquid nitrogen, the temperature decrease due to thermodynamic effect was predicted at least qualitatively, but its quantitative accuracy was not ensured. Related to the fair prediction in the case of liquid nitrogen, one of the problems in the application of the present cavitation model would be that the typical size distribution of bubble nuclei in inception has not been understood experimentally and theoretically in the case of cryogenic fluids, and more appropriate modeling of the inception in cryogenic fluids is one of the important near future works.