Vortex Lattice Method Investigation of Tip-Leakage Flow

Abstract

The use of a Vortex Lattice Method (VLM) is investigated on a tip-leakage flow single blade configuration (NACA 0012) for a wide range of tip gaps. The aim is to estimate the circulation of the tip-leakage vortex (TLV) detaching from the blade. The evaluation of that circulation without adding viscous effects to the potential method is comparable with the experimental measurements for the largest gaps but requires a diffusive model for the smaller gaps. A new diffusive model is constructed and integrated to the VLM, yielding a very good match with the experiment on the circulation for the whole tip gap range. This result indicates that for thin blades, the development of the TLV can be described in two stages: (i) a potential formation, (ii) a viscous diffusion leading to a decay once the vortex is detached from the blade.