Euler Lagrange Modelling of Cavitation Erosion


Cavitation erosion is frequently observed in marine and hydraulic engineering, e.g. ship propellers and rudders, pumps or turbines. Due to the severe risks associated to operations under sustained erosive cavitation, the accurate prediction of cavitation erosion is of great importance from an industrial point of view. Therefore cavitation erosion has been intensively investigated experimentally and theoretically since the middle of the last century. The two primary mechanisms responsible for erosion are the radiated pressure induced by the collapse and rebound of spherical bubbles, the latter driven by the compression of small residual amounts of incondensable gas, and micro-jets generated by non-symmetric collapses in the near-wall region. In practical fluid-engineering applications both types of erosion mechanisms are present and it is not always possible to distinguish between them. Experimental evidence  indicates that micro-jets are associated to bubbles collapsing within splitting distance from the wall, whereas spherical collapses are more frequently meet for bubbles located further away from the wall.




In the present work cavitating flows are modeled using Euler-Lagrange multiphase approach. In this approach the fluid phase solution follows from Eulerian conservation equations and the vapor phase is modeled with a discrete bubble model considering the dynamics of individual bubbles driven by the surrounding flow field. Discrete bubble model allow to consider bubble deformation, bubble break-up, bubble/bubble- or bubble/wall-interactions. The Euler-Lagrange approach has been extended in the present work to assess cavitation erosion. Two types of bubble collapses - spherical and micro-jet are considered, providing information on surface pressure loads which can be used to assess erosion. 





Simulated cavitation pattern (left; vapour 50% vapor) and detected collapse events (right; bubble size indicates pressure magnitude)



The project is funded by Deutsch Forschungsergebnisse Gemeinschaft. 


Dr. Sergey Yakubov
Prof. Dr.-Ing. Thomas Rung