Capturing Secondary Cavitation – A Step Towards Numerical Assessment of Cavitation Nuisance

Abstract

Numerical simulations using incompressible Large-Eddy Simulation together with a mixture assumption and a finite-rate mass transfer model demonstrate the presence of several cavitation mechanisms important for cavitation nuisance of hydrodynamic machinery such as marine propellers and power turbines. One of such mechanisms is brought about by re-entrant jets, which can cut sheet cavities and thus lead to shedding and travelling cavities which in turn may cause nuisance as they collapse. However, severe erosion and noise generation also stem from the formation and development of small scale structures called secondary cavitation, formed e.g. in shear layers through vortex roll-up, which are also important for cavitation nuisance risk. The extent of the resolution of the secondary cavitation in the computational setting is discussed. Cavitation on a NACA0015 foil at 6° angle of attack and σ = 1.0 in a three-dimensional domain is studied.