A comparison of nonlinear actuator disk methods for the performance analysis of ducted marine propellers

This paper presents the validation of a generalised semi-analytical actuator disk model as applied to the study of the flow around ducted propellers. The method, which returns the exact solution as a superposition of ring vortex, duly accounts for the rotation of the wake, the convergence of the slipstream, and the nonlinear mutual interaction between the duct and the propeller. Furthermore, it can deal with an arbitrary radial distribution of the load and ducts of general shape. In order to validate the previously mentioned actuator disk model, results obtained through it are compared with those provided by the so-called "CFD actuator disk method". The latter is a widely diffused tool for the analysis of the flow around open and ducted propellers which models the rotor by means of radial profiles of blade forces distributed over a disk surface. In this paper, evidence has been given of the excellent agreement between the results of the two methods. Thanks to its extremely reduced computational cost the semi-analytical method is well suited to be integrated into design systems based on the repeated analysis scheme of hierarchical type.