The objectives of this study are to propose exact numerical methods for the compressible cryogenic cavitating flows and investigate the cavitation behaviors and vortex structures. A numerical modeling framework including large eddy simulations, vapor-liquid equations of state and a modified mass transport model is presented in this paper. The modified transport model is proposed based on the convective heat transfer, in which the convective heat transfer coefficient is associated with the material properties and local temperature. To validate the applicability of the modified model, the liquid nitrogen cavitating flows in the inertial and thermal modes ( s ≈0.50, Tthroat =77.24K and Tthroat =85.23K) are simulated respectively. Meanwhile, the influence of thermodynamic effects on the compressibility is investigated. The numerical method is further utilized to visualize the detailed cavity and vortex structures in the different cavitating flow patterns ( Tthroat ≈77K, s =0.58, 0.39, 0.18). The results show that the predicted cavity structures with the modified mass transport model agree better with the corresponding experimental data. For the thermal mode, since the significant thermal effects restrain the development of cavity, the area of the low sound speed region is smaller than that of the inertial model. And the value of the minimum sound speed is larger. So that the Mach number in the cavitation region is reduced. Therefore, the compressibility of the liquid nitrogen cavitation in the thermal mode is weaker. For the different cavitating flow patterns, the core region of attached cavities near the throat remains stable during an evolutionary cycle.

Liquid hydrogen is considered clean energy and is usually pressurized by cryogenic pumps in various industries. To ensure the safe operation of cryogenic pumps, the inducer is installed in front of the pump to improve the impeller inlet pressure but causes cavitation instabilities. This paper aims to investigate the mechanisms of the tip leakage vortex (TLV) cavitating flow in a cryogenic inducer with liquid nitrogen. The large eddy simulations model was used to analyze the thermodynamic effects on the tip leakage vortex cavitation (TLVC). The cavity structure and the pulsation mechanisms of the TLVC were analyzed through the flow characteristics and the vorticity transportation process. The predicted cavitation performance is in good agreement with the experimental measurements. The numerical results showed that the TLVC is suppressed and forms the separation point between the primary TLVC and the secondary TLVC due to the thermodynamic effects. The inhibition rate of the vapor volume fraction at the leading edge is 30%. The pressure fluctuations are caused by the propagation pattern of the detached cavity interacting with the adjacent blade periodically. The velocity triangles near the detached cavity were proposed to reveal the development of the TLVC. It indicates that TLVC instability is caused by the periodic coupling effect of the cavity development, the flow rate magnitude, and the local incidence angle variation. The vorticity transport equation is utilized to investigate the interaction of cavitation and vortex. Comparing the three terms reveals that the stretching and bending term dominates in the vorticity production of the TLV cavitating flow. The dilatation term controls the transportation of vorticity inside the TLV cavity, while the contribution of the baroclinic torque term is negligible in comparison to the other terms. This study provides a reference for optimizing the TLV cavitating flow and instabilities for designing the cryogenic pump.