| Thermal effects substantially impact the cavitation dynamics of cryogenic fluids. The present study strives towards developing an effective computational strategy to simulate cryogenic cavitation aimed at liquid rocket propulsion applications. We employ previously developed cavitation and compressibility models, and incorporate the thermal effects via solving the enthalpy equation and dynamically updating the fluid physical properties. The physical implications of an existing cavitation model are reexamined from the standpoint of cryogenic fluids, to incorporate a mushy formulation, to better reflect the observed "frosty" appearance within the cavity. Performance of the revised cavitation model is assessed against the existing cavitation models and experimental data, under non-cryogenic and cryogenic conditions.; Steady state computations are performed over a 2D hydrofoil and an axisymmetric ogive by employing real fluid properties of liquid nitrogen and hydrogen. The thermodynamic effect is demonstrated under consistent conditions via the reduction in the cavity length as the reference temperature tends towards the critical point. Justifiable agreement between the computed surface pressure and temperature, and experimental data is obtained. Specifically, the predictions of both the models are better; for the pressure field than the temperature field, and for liquid nitrogen than liquid hydrogen. Global sensitivity analysis is performed to examine the sensitivity of the computations to changes in model parameters and uncertainties in material properties.; The pressure-based operator splitting method, PISO, is adapted towards typical challenges in multiphase computations such as multiple, coupled, and non-linear equations, and sudden changes in flow variables across phase boundaries. Performance of the multiphase variant of PISO is examined firstly for the problem of gallium fusion. A good balance between accuracy and stability is observed. Time-dependent computations for various cases of cryogenic cavitation are further performed with the algorithm. The results show reasonable agreement with the experimental data. Impact of the cryogenic environment and inflow perturbations on the flow structure and instabilities is explained via the simulated flow fields and the reduced order strategy of Proper Orthogonal Decomposition (POD). |
