Simulation of Viscous Flow around a Ducted Propeller with Rudder Using Different RANS-Based Approaches

Within EU Project SUPERPROP, the flow around a ducted propeller located in front of a rudder has been numerically simulated and analyzed using different RANS approaches. The presence of the rudder makes the velocities at the propeller plane non-symmetric, which results in a flow of unsteady nature. Unsteady flows can sometimes be approximated using simplifications which reduce the hydrodynamic problem to a steady-state one, whilst the prediction accuracy remains reasonable. The main two simplifications are the mixing plane approach and the quasi-steady approach. This paper compares calculations made with these two approaches to timeaccurate computations. The computations are performed on a ducted propeller unit of a fishing vessel subject to investigation within EU project SUPERPROP. Comparison of thrusting forces obtained with the different approaches is presented for the various components of the propulsion unit. Details of the flow at particular zones illustrate the character of the simplifications for this particular configuration. RANS code FINFLO was used in the calculations.