Inclination angle effect on ventilation pattern and trailing wake formation of the partially submerged propeller

Partially submerged propellers function in two-phase condition, i.e. each propeller blade enters water once in each revolution so the thrust and torque of each blade hit maximum level and then become around zero. Surface-piercing propeller investigated in this work is a new geometry that the main purpose of its design has been to achieve higher hydrodynamic performance; minimizing energy loss by reducing of the volume fraction of the water adhered to the exiting blade from the water surface. In this article, Reynolds-Averaged Navier–Stokes computations based on finite volume method (FVM) was applied to investigate force excitation, ventilation pattern and wake formation of the partially submerged propeller under inclination angle. Two-phase flow field equations were solved using homogenous Eulerian multiphase model by sliding method. To solve two-phase flow field at the free surface accurately and deal with free surface effects in calculations, CFX free surface model based on volume of fluid (VOF) approach was used. The accuracy of the numerical method was verified using series of simulations on SPP-841B propeller with existing experimental measurements. Comparison between simulated and measured SPP-841B open characteristics as well as ventilation pattern of the key blade indicated a reasonable agreement with experimental data and observations. Based on obtained data, with an increase in shaft inclination angle, propeller thrust and torque coefficients increased, whereas the propeller efficiency was decreased.