Analysis of different propeller ventilation mechanisms by means of RANS simulations

Based on the experiments of Shiba (1953) and Koushan (2006) an analysis of different types of propeller ventilat ion was performed by means of numerical simulations. The aim of this work is to analyse the ventilation mechanisms, whose deeper understanding would improve the ability to predict them. Ventilation can seriously damage mechanical components of an engine, eventually leading to its failure. The commercial RANS code Fluent (2006) has been used to solve the viscous, incompressible, two-phase flow. The rotation of the propeller has been implemented both with a Multiple Reference Frame model and using Sliding Mesh. Results of a fully ventilating case, in terms of blade and propeller loadings, are presented and discussed with the ai d of flow visualization at different angular positions. For a well submerged propeller, a discussion about ventilation induced by a free-surface vortex is presented.