Large Eddy simulation of ventilated cavitation with an insight on the correlation mechanism between ventilation and vortex evolutions

• Published in: Applied Mathematical Modelling 2021-01, Vol.89, p.1055-1073
• Main Authors: Yu, An, Qian, Zhaohui, Wang, Xincheng, Tang, Qinghong, Zhou, Daqing
• Format: Article
• Language: English
• Subjects: Aerodynamics; Air cavity fluttering; Cavitation; Downstream effects; Evolution; Fluid dynamics; Fluid flow; Flutter; Holes; Large eddy simulation; Morphology; Ventilated cavitation; Ventilation; Vortex evolution; Vortex shedding; Vortex/turbulence interaction; Vortices; Vorticity
• ISSN: 0307-904X; 1088-8691; 0307-904X
• DOI: 10.1016/j.apm.2020.08.011

•The ventilated cavitation under natural cavitation condition is simulated by LES with Cartesian cut-cell mesh.•The evolution of two contrarotating vortex and its correlation mechanism with ventilated cavity are analyzed.•The typical structure and evolution mechanism of ventilated cavity was summarized.•The physical mechanisms for the interactions of velocity pulsation, turbulence kinetic energy and vorticity are clarified. In this paper, the unsteady natural cavitation and ventilated cavitation are investigated with the large eddy simulation method. The predicted cavity morphology and evolution process before and after ventilation agree well with the available experimental data. The results indicate that in natural cavitation, the formation of a U-type cavity is closely related to the separation of a re-entrant jet and the effect of vortex evolution, while the local high pressure region plays an important role in shaping the appearance of the primary and secondary U-type cavity in the process of moving downstream. During ventilated cavitation, the deflation effect of the air drives the pair of vortices to shed periodically, accompanied by the downstream transportation of vorticity, and promotes the formation of arched air cavities. In the anticlockwise vortex shedding region, the vortex dilatation term has a concentrated distribution on the air-liquid interface which is due to the intense mixing of the phases. Further analysis demonstrates that, in the air cavity fluttering area, the magnitude of the velocity pulsation produces a significant downward tendency due to the gradual weakening of vortex intensity. Moreover, the interaction between vortices and turbulence shows a high degree of consistency in the wake flow.