Self-Excited Roll Oscillations of Non-Slender Wings
Final rept. 1 Jul 2006-1 Jul 2009
BATH UNIV (UNITED KINGDOM) DEPT OF MECHANICAL ENGINEERING
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The main objective of this research is to understand the free-to-roll aerodynamics and self-excited roll oscillations of low aspect ratio wings. Generic thin, flat-plate wing planforms for unmanned air vehicles and micro air vehicles were considered. Slender and nonslender delta wings with sweep angles between 40-deg and 70-deg, cropped delta wings, rectangular wings with aspect ratios of AR 2 and 4, Zimmerman, and elliptical wings were investigated. Measurements of roll history, flow visualization, and PIV measurements were conducted in the free-to-roll experiments in a wind tunnel. Nonzero trim roll angles and self-induced roll oscillations were observed for most of the wings. Leading-edge vortices, tip vortices and separation bubbles play an important role in the free-to-roll aerodynamics. Hysteresis and time lag effects are behind the observed roll oscillations. The results may be useful in improving the maneuverability and gust response of unmanned air vehicles.
- Electricity and Magnetism
- Fluid Mechanics
- Atomic and Molecular Physics and Spectroscopy