A General Free Wake Geometry Calculation For Wings and Rotors

A general free wake geometry calculation for wings and rotors is presented. The method, which has been implemented in CAMRAD II, gives good performance and airloads correlation at advance ratios of 0.05 and above, with reasonable computation speed. The wake geometry distortion can be calculated for multiple wings, multiple rotors, and non-identical blades; for all wake structures, including multiple rolled-up trailed vorticity and inboard sheets as well as tip vortices; using the same wake model as the induced velocity calculations; for transients as well as the trim solution. The theoretical approach is described. Results are presented for rotor airloads, flapping, and performance, including comparisons with a common wake geometry method and with measured data. Calculated wake geometries are shown for a nonrotating wing, a single rotor, multiple main rotors, and a wind turbine.