Investigation of vortex development on a pitching slender body of revolution

A computational study of the unsteady flow about a pitching 3.5-caliber tangent ogive forebody is presented. The flow is simulated using the full three-dimensional unsteady Navier-Stokes equations and a time-accurate implicit algorithm. Effects of grid resolution and a comparison of solutions using full Navier-Stokes and the thin-layer approximation are included. The forebody is simulated in a "pitch-up to 20 deg and hold" maneuver, and two different pitch-axis locations are used in the study. Examination of the unsteady vorticity field for the pitch-up cases reveals the formation of strong shear layers as the body decelerates, and their roll-up into vortical structures in a process similar to that observed in airfoil dynamic stall. Pronounced vortex/surface interactions are seen which produce multiple secondary separation regions, ejection of vorticity from the surface, and embedded regions of high suction.

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