WIND-TUNNEL TEST 10 LEADING-EDGE VORTEX OF LOW-ASPECT-RATIO FLAPPING PLATES

A leading-edge vortex attaching to the suction side of a wing was one unique phenomenon explaining a high lift force of sweptback aerodynamic devices as well as the wings of biological flyers. In forward flight, however, various parameters and their relationships at low Reynolds number complicate the study. Here, we prepared a servo-driven robotic arm, force/torque transducers for six axes, and several model plates with different aspect ratios for the wind tunnel test. A way of eliminating an inertial force and decomposing steady and unsteady components were also discussed. In a preliminary test, we found that a sweptback angle provided a better lift for all the plates regardless of aspect ratio. The plate with an aspect ratio of three outperformed the others with a sufficient sweptback angle, as a previous study found. A further test for the plates in sweeping motion showed an increase in the lift with time at a non-zero sweptback angle during the stroke; this is also in line with a previous study. The test with two different thickness plates clarified the potential of the approach of how to remove inertial forces from the measured values in motion.