Numerical Study of the Behaviors of Ventilated Supercavities in a Periodic Gust Flow

Abstract

We conducted a numerical simulation of ventilated supercavitation from a forward-facing cavitator in unsteady flows generated by a gust generator under different gust angles of attack and gust frequencies. The numerical method is validated through the experimental results under specific steady and unsteady conditions. It has been shown that the simulation can capture the degree of cavity shape fluctuation and internal pressure variation in a gust cycle. Specifically, the cavity centerline shows periodic wavelike undulation with a maximum amplitude matching that of the incoming flow perturbation. The cavity internal pressure also fluctuates periodically, causing the corresponding change of difference between internal and external pressure across the closure that leads to the closure mode change in a gust cycle. In addition, the simulation captures the variation of cavity internal flow, particularly the development internal flow boundary layer along the cavitator mounting strut, upon the incoming flow perturbation, correlating with cavity deformation and closure mode variation. With increasing angle of attack, the cavity exhibits augmented wavelike undulation and pressure fluctuation. As the wavelength of the flow perturbation approaches the cavity length with increasing gust frequency, the cavity experiences stronger wavelike undulation and internal pressure fluctuation but reduced cavitation number variation.

Large Eddy Simulation Investigations of Periodic Cavitation Shedding With Special Emphasis on Three-Dimensional Asymmetry in a Scaled-Up Nozzle Orifice

“…Therefore, the current research focus is not on the accurate value of cavity length, but on the ability of the numerical method to reproduce cavitation regimes by comparing the variation trend of cavitation length. In the present research, the cavity boundaries are identified with a reasonable value of 10% vapor volume fraction, which has been well adjusted and widely used [43,69].…”

Transient separation and fluctuation of turbulent flow in an axisymmetric U-turn channel perturbed by periodically passing gust inflow

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