PRELIMINARY EXPERIMENTS OF A FLAPPING WING IN THREE-DEGREE-OF-FREEDOM MOTIONS

摘要

A preliminary water tunnel experiment was conducted on an insect wing performing three degree-of-freedom (3DOF) motions. A bi-fold five-component strain-gauge balance has been developed to measure the aerodynamic behavior of insect's flapping wings. It has been found that at low- to mid-range angles of attack, the normal force and pitching moment of the wing increase as the angle of attack increases. While at high angles of attack, the phase shift between the motion and the aerodynamic loads becomes obvious. The maximum normal force appears some distance ahead of the maximum angle of attack and decreases dramatically thereafter as the angle increases further. Introducing second and third degrees of freedom motions could further increase the maximum normal force compared with one-degree-of freedom motion, indicating possible delayed stall caused by the additional motion.