Large eddy simulation of the periodic cavity evolution and the turbulence characteristics around a Delft Twist-11 hydrofoil

Abstract

In the present investigation, the LES WALE method along with the Zwart cavitation model is utilised to predict the cavitating flow around a Delft Twist-11 hydrofoil and the numerical results show a reasonable agreement with the experimental data. A novel elucidation is provided to the formation of the U-type structure and the Lumley method is introduced into the numerical simulation which can offer a validation of the simulation. The evolution of the cavity structure, especially the formation and development of U-type structures, was investigated thoroughly with the assistant of the Ω method, the Lamb vector, and the vorticity transport equation (VTE). As a third-generation vortex identification, Ω = 0.52 captures the vortex structure during the cavity evolution exhaustively. The cavitation-vortex interaction impacts the cavity evolution profoundly. The primary weak vortex and the secondary weak vortex both have a significant effect on the cavity shedding and the formation of the U-type structure. Moreover, the stretching action and the vorticity bearing motion described by the Lamb vector divergence clarify the formation of the special cavity structure in depth. In virtue of the mean velocity, Reynolds stresses, Lumley triangle, and Lumley distance, the turbulence characteristics were also investigated carefully. The cavitating motion plays a significant role in the turbulence velocity fluctuation and turbulence anisotropy around a twisted hydrofoil.

KEYWORDS:

• Cavitation evolution
• large eddy simulation
• Delft Twist-11 hydrofoil
• unsteady cavity structure

Acknowledgements

This research was funded by the National Natural Science Foundation of China (Project No. 51806058 and 51839008) and the Fundamental Research Funds for the Central Universities (Project No. B200202170).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 51806058,51839008]; Fundamental Research Funds for the Central Universities: [Grant Number B200202170].