Numerical assessment of cavitation erosion risk using incompressible simulation of cavitating flows

Artikel i vetenskaplig tidskrift, 2021

In this paper, a numerical method to assess the risk of cavitation erosion is proposed, which can be applied to incompressible simulation approaches. The method is based on the energy description of cavitation erosion, which considers an energy transfer between the collapsing cavities and the eroded surface. The proposed framework provides two improvements compared with other published methods. First, it is based on the kinetic energy in the surrounding liquid during the collapse instead of the potential energy of collapsing cavities, which avoids the uncertainty regarding the calculation of the collapse driving pressure in the potential energy equation. Secondly, the approach considers both micro-jets and shock-waves as the mechanisms for cavitation erosion, while previous methods have taken into account only one of these erosion mechanisms. For validation, the proposed method is applied to the cavitating axisymmetric nozzle flow of Franc et al. (2011), and the predicted risk of cavitation erosion is compared with the experimental erosion pattern. This comparison shows that the areas predicted with high erosion risk agree qualitatively well with the experimental erosion pattern. Furthermore, as the current method can be used to study the relationship between the cavity dynamics and the risk of cavitation erosion, the hydrodynamic mechanism responsible for the high risk of cavitation erosion at the inception region of the sheet cavity is investigated in detail. It is shown for the first time that the risk of cavitation erosion in this region is closely tied to the separation of the flow entering the nozzle.