Propeller diameter selection based on numerical analysis of wake and induced-pressure on blades and on tunnel stern surface

Aim of this work is the analysis of the flow in the stern region by simulations. In this work will be reported the numerical analysis of the flow around the propeller working in a stern-tunnel of a fully appended twin–screw fast displacement M/Y. Particularly, the aim of the study is the evaluation of the effects on the pressure and on the wake in the tunnel region, due to the diameter variations of the propellers. The analysis is organized in two stages. The first stage is the preliminary validation analysis, in order to characterize the initial propeller by Reynolds Averaged Navier Stokes (RANS) simulations of open water propeller tests. The second stage is the Unsteady RANS simulations, performed in the time domain, in order to investigate the interaction between tip clearance reductions and increasing of pressure pulsations on the tunnel’s surface.