A study of the dynamics of arrays of trailing vortices

An experimental study ofthe dynamics of trailing vortices in arrays ofvarious configurations was conducted in a large towing tank employing a combined approach of Digital Particle Image Velocimetry and Flow Visualization techniques. Several NACA wing geometries were used to generate trailing vortices at chord-based Reynolds numbers of 0(103-1 Os) and at circulation-based Reynolds numbers of 0(103-104 ). The apparatus was designed in order to change the parameters: vortex separation, vortex strength and towing speed. The configurations chosen for this work allowed a study of the turbulent merger process of two co-rotating vortices of equal and unequal strength. This data could then be compared with several other results from the literature and further conclusions were drawn in particular on the effect ofvarying vortex parameters and ofturbulence on the merger process. The dynamics of two counter-rotating vortices of both equal and unequal strength were also investigated. More specifically, the Crow-Instability and its instability wavelengths were studied. In addition, the rapid annihilation oftwo counter-rotating vortices ofunequal strength was investigated. The dynamics of arrays of three vortices were studied with a large set of experiments. The effect of a third vortex - essentially representing a rotating strain field plus a factor of induction - on the merger process was mapped and time scales were compared. Several flow configurations resulting in special vortex wakes (e.g. splitting of a vortex) were studied in detail.EThOS - Electronic Theses Online ServiceGBUnited Kingdo