Publications

Experiments and computations of roll torque induced by vortex-fin interaction

Peterson, C.W.; Wolfe, Walter P.; Payne, Jeffrey L.

An experiment was conducted in Arnold Engineering Development Center's 16-ft transonic wind tunnel to measure the dependency of vortex-induced counter torque upon J (the ratio of spin motor jet dynamic pressure to freestream dynamic pressure), Mach number, Reynolds number, angle of attack and roll orientation, spin motor nozzle configuration, and fin cant angle. Counter torque data and Laser Vapor Screen images confirm that J is the dominant parameter for correlating counter torque produced by a given vehicle configuration, flight condition, angle of attack and roll orientation. At M = 0.8 (with no shock waves in the flow), we observed a monotonie variation of the counter torque coefficient CCT with J that is independent of Reynolds number but dependent on angle of attack and the orientation of the fins with respect to the spin motor nozzle azimuthal location. At M = 0.95 and 1.1, measured values of CCT were strongly influenced by changes in Reynolds number, suggesting that shock-boundary layer interaction may be present.