A Comparison of Panel Method and RANS Calculations for a Ducted Propeller System in Open-Water

In this paper, a comparison between results of a panel method and a RANS solver is made for a ducted propeller system in open-water. The panel method calculations were made at IST with the panel code PROPAN. Different wake models are used in the inviscid computations: rigid wake model with prescribed wake geometry and a vortex pitch wake alignment model without and with a duct boundary layer correction. For the flow in the gap region a closed gap width and a gap flow model with transpiration velocity are considered. The RANS calculations were carried out at MARIN with the RANS code ReFRESCO. A comparison of the blade and duct pressure distributions, wake geometry and thrust and torque coeficients is presented. In general, good agreement of the pressure distributions, wake geometries and force coefficients between the two codes is achieved. A reasonable agreement between the inviscid blade wake position and the blade wake viscous vorticity field is obtained when using the wake alignment model. It is seen that the correlation improves when introducing the duct boundary layer correction. The force coefficients are also compared with experimental data available from open-water tests. A reasonable to good agreement is seen for the thrust and torque coefficients over the entire openwater range.