Generation of a wingtip vortex pair using a pressure-side fin

We present results from a combined experimental and numerical investigation of the flow around rectangular NACA 0012 wing, whose tip geometry is modified by addition perpendicular fin. The purpose this modification to generate system two closely-spaced concentrated vortices, instead familiar single trailing vortex. Experiments were carried out in water tunnel, where velocity measurements made near wake wing using Stereoscopic Particle Image Velocimetry, order determine characteristics vortex pair. Various configurations tested changing position, dimensions angle attack It was found that fin could strong secondary only when placed on pressure side wing. Visualisations surface streamlines oil painting wind as well simulations wingtip region, show separation occurs with suction side, even at low angles attack. Both experiments used influence parameter variations pair, respect its circulation ratio distance. Whereas co-rotating pairs similar be generated easily, fin's ability produce counter-rotating vortices rather limited. current have relevance context reducing impact which for rotor can lead blade-vortex interactions, causing fatigue aerodynamic noise.