Numerical Prediction of Cavitating Flow on a Two-Dimensional Symmetrical Hydrofoil and Comparison to Experiments

Abstract

This paper presents comparisons between two-dimensional (2D) CFD simulations and experimental investigations of the cavitating flow around a symmetrical 2D hydrofoil. This configuration was proposed as a test case in the "Workshop on physical models and CFD tools for computation of cavitating flows" at the 5th International Symposium on cavitation, which was held in Osaka in November 2003. The calculations were carried out in the ENSTA laboratory (Palaiseau, France), and the experimental visualizations and measurements were performed in the IRENav cavitation tunnel (Brest, France). The calculations are based on a single-fluid approach of the cavitating flow: the liquid/vapor mixture is treated as a homogeneous fluid whose density is controlled by a barotropic state law. Results presented in the paper focus on cavitation inception, the shape and the general behavior of the sheet cavity, lift and drag forces without and with cavitation, wall pressure signals around the foil, and the frequency of the oscillations in the case of unsteady sheet cavitation. The ability of the numerical model to predict successively the noncavitating flow field, nearly steady sheet cavitation, unsteady cloud cavitation, and finally nearly supercavitating flow is discussed. It is shown that the unsteady features of the flow are correctly predicted by the model, while some subtle arrangements of the two-phase flow during the condensation process are not reproduced. A comparison between the peer numerical results obtained by several authors in the same flow configuration is also performed. Not only the cavitation model and the turbulence model, but also the numerical treatment of the equations, are found to have a strong influence on the results.

Numerical study of unsteady flow around a cavitating hydrofoil

“…The other way to model cavitation process is by the so called barotropic state law that links the density of vapor-liquid mixture to the local static pressure. The model was proposed by Delannoy and Kueny (1990) and later widely used by S Song et al (1998), Hofmann et al (1999), Lohrberg et al (2002) and Coutier-Delgosha et al (2003). The results obtained with the barotropic cavitation model show very good correlation to the experiments but the past simulations lacked in robustness of the numerical algorithms, which resulted in numerical instability and sometimes, poor convergence.…”

An improved progressive preconditioning method for steady non‐cavitating and sheet‐cavitating flows

“…If the cell is full of pure vapour, then = 1 and if a cell is totally occupied by pure liquid, = 0. The fluid density is controlled by a barotropic state law ( p) that links the fluid density variations to the local static pressure as follows [21,31,32]:…”

Numerical simulation of unsteady three-dimensional sheet cavitation

“…However, when a barotropic relation is employed, then the gradients of density and pressure are always parallel, hence the baroclinic torque is zero. Nevertheless, many other researchers have applied this model with different barotropic laws, see Reboud & Delannoy [157], Hoeijmakers et al [95], Arndt et al [16], Coutier-Delgosha et al [44,47,45,46,48], Reboud et al [156], Qin [154] and Sinibaldi et al [183]. In appendix F a barotropic flow model developed in our group is described, see Veldhuis [207] and Koop et al [113].…”