Development of an Unsteady Vortex Lattice Method to Model Propellers at Incidence

Abstract

The complex aerodynamics of a propeller at incidence involve multiple asymmetric flow conditions around the disk, with each originating from different physical phenomena. These asymmetries give rise to in-plane forces and out-of-plane moments that are difficult to model with traditional low-order computational aerodynamics methods. This paper presents a three-dimensional unsteady vortex lattice method with a free vortex ring wake formulation that has been developed to model these effects for propellers at incidence. Convergence quality is investigated with respect to simulation time, grid resolution, and time-step resolution. Solution accuracy is evaluated by comparing to computational fluid dynamics (CFD) analyses. Good agreement was found with CFD results. The paper concludes with a discussion on the challenges of modeling propellers at incidence with vortex lattice methods.