Abstract
The numerical simulation of unsteady cavitation flows is sensitive to the selected models and associated parameters. Consequently, three Reynolds Average Navier-Stokes (RANS) turbulence models and the Zwart cavitation model were selected to assess their performance for the simulation of cloud cavitation on 2D hydrofoils. The experimental cavitation tests from a NACA65012 hydrofoil at different hydrodynamic conditions were used as a reference to tune the modeling parameters and the experimental tests from a NACA0015 were finally used to validate them. The effects of near wall grid refinement, time step, iterations and mesh elements were also investigated. The results indicate that the Shear Stress Transport (SST) model is sensitive to near wall grid resolution which should be fine enough. Moreover, the cavitation morphology and dynamic behavior are sensitive to the selection of the Zwart empirical vaporization, Fv , and condensation, Fc , coefficients. Therefore, a multiple linear regression approach with the single objective of predicting the shedding frequency was carried out that permitted to find the range of coefficient values giving the most accurate results. In addition, it was observed that they provided a better prediction of the vapor volume fraction and of the instantaneous pressure pulse generated by the main cloud cavity collapse.
Highlights
Cavitation is a topic of concern in the design and operation of a wide variety of hydraulic machinery and systems due to its negative effects like erosion, noise, vibrations and performance drop
The results indicate that the Shear Stress Transport (SST) model is sensitive to near wall grid resolution which should be fine enough
It has to be noted that, unlike the previous works summarized in Table 1 in which most of the investigations have been based on steady state simulations, in our study we have focused on the shedding process of the cloud cavitation around hydrofoils
Summary
Cavitation is a topic of concern in the design and operation of a wide variety of hydraulic machinery and systems due to its negative effects like erosion, noise, vibrations and performance drop. Tseng and Wang (2014) modified the coefficients of the Zwart model into a dimensionless form, and determined a coefficient range based on the experiments of a hemispherical projectile (Rouse & McNown, 1948) and of the NACA66(MOD) hydrofoil (Shen & Dimotakis, 1989), as well as the Clark Y hydrofoil (Wang, Senocak, Shyy, Ikohagi & Cao, 2001) They stated that their proposed range of values improved the generality and reduced the sensitivity of the numerical results to the cavitation model. It has to be noted that, unlike the previous works summarized in Table 1 in which most of the investigations have been based on steady state simulations, in our study we have focused on the shedding process of the cloud cavitation around hydrofoils
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
