Modeling of turbulent cavitating flows

The goal of this dissertation is to establish a predictive tool for turbulent cavitating flows, including those under cryogenic conditions with noticeable thermal effects. The modeling framework consists of a transport-based cavitation model with ensemble-averaged fluid dynamics equations and turbulence closures. The cavitation models used in this study include a phenomenological model with empirical supports and an interfacial dynamics model that utilizes continuity and force balance across the interfaces. For the turbulence closure, a filter-based approach and density correction approach has been imposed to the two equation k-epsilon model.;The reported experimental investigations contain insufficient details regarding the inlet turbulence characteristics of the flow field. However, the inlet turbulent quantities can substantially impact the outcomes because the viscous effect can modify the effective shape of a solid object, which causes noticeable variations in the predicted multiphase flow structures. A filter-based turbulence closure is utilized to reduce the impact of the inlet turbulent quantities based on the local resolution. Its effectiveness is confirmed by both isothermal and cryogenic cavitation. In addition, the thermal effect and the competing effect between the cavitation number and the density ratio effects are investigated by evaporation and condensation dynamics under the cryogenic conditions. Based on the surrogate-based global sensitivity analysis under cryogenic conditions, one can assess the role of model parameters and uncertainties in material properties. It is revealed that variables represented for the evaporation rate are more critical than those for the condensation rate. Furthermore, the recommended model parameter values are optimized by tradeoffs between pressure and temperature predictions.;For unsteady cavitating flows, the phenomenological model and interfacial dynamics model are utilized by the turbulence closure with the filter-based approach, the density correction approach, and a hybrid approach that blends the previous two methods. It is discovered that the eddy viscosity near the closure region can significantly influence the capture of the detached cavity. From the experimental validations, no single model combination performs best in all aspects. Furthermore, the implications of the parameters contained in the different cavitation models are investigated. The phase change process is more pronounced near the detached cavity, which is more substantial in the interfacial dynamics model.