A systematic study of side-wall interference effects on delta wing aerodynamics

This paper presents a series of experiments designed to investigate the effect of side-walls on the wind tunnel testing of delta wings. In the study, smoke flow visualization, Particle Image Velocimetry and pressure measurements are used to investigate the effect of the ratio of model span to tunnel width on vortex position, strength and breakdown location. Rather than using a series of different sized models in the same wind tunnel, the present study utilizes 'dummy' walls that extend fore and aft of the delta wing model and that can be moved towards and away from the model. This approach avoids changes in flow topology due to subtle changes in geometry from model to model. It is found that the side-wall position influences the location of vortex breakdown, the vortex strength, location and geometry and also the pressure distribution over the wing.