Aerodynamic Correlations for a Fin with a Vortex- Induced Angle of Attack

An experimental program has been conducted using fins mounted on one wall of a transonic wind tunnel to study the interaction of a trailing vortex with a downstream control surface. Data are collected using two primary diagnostics, a fin balance mounted on the downstream fin to measure the aerodynamic forces of the interaction, and stereoscopic Particle Image Velocimetry applied in past work to obtain the properties of the vortex responsible for the interaction. Both a lateral offset between the two fins and the upstream fin angle of attack modify the forces upon the trailing fin through the same phenomenon, by altering the induced angle of attack upon the downstream fin. The force and moment coefficients on the downstream fin were found to correlate well with its total angle of attack as the data, in most cases, collapsed to a single curve in all three components when plotted against total angle of attack. This makes it possible to estimate the forces upon a downstream fin when only the single fin aerodynamic characteristics and vortex properties are known