Experimental investigations on limit cycle wing rock of slender wings

Abstract

The phenomena of wing rock of a delta wing with 80-deg sweep has been investigated through a comprehensive series of experiments. Two unique experimental apparatus have been developed for the investigation. A freeto-roll system was developed using an air-bearing spindle that allowed the isolation of applied torques due to the flowfield. An unsteady pressure acquisition system was also developed in order to measure the unsteady surface pressure distributions acting on the wing during wing rock motion. Experimental measurements include motion characteristics obtained from motion history plots, static and dynamic flow visualization of vortex position and vortex breakdown, static surface flow visualization, and steady and unsteady surface pressure distributions. Correlation using the different sources of data provides insight into mechanisms that are most likely to cause the wing rock motion. Nomenclature A = wing rock amplitude b = wing span C, = roll moment coefficient C'i = roll moment contribution from a single chord station