A Semi-Empirical Correction for the Vortex Core Effect on Hovering Rotor Wake Geometries

A semi-empirical correction for the vortex core effect on hovering rotor wake geometries is presented. The results show that with this effect included, the tip vortex geometry in the near wake can be calculated with much better accuracy for one-, two-, three-, and four-bladed rotors than has been previously possible. The method breaks down for six-bladed rotors and this appears to be due to the use of the lifting line rather than the lifting surface model for the blade.