Roles of wing flexibility and kinematics in flapping wing aerodynamics

Insects are excellent fliers because of their ability to generate precise wing kinematics and deform wings for the sufficient production unsteady aerodynamic forces. Most previous studies on effects aerodynamics have been limited use rigid wings, leaves contribution flexibility unknown. Here, an experiment was conducted investigate effect varied sweep duration timing rotation characteristics hovering flexible at Re 104. This study found that forces generated by showed a conspicuous phase delay, which more sensitive change in than rotation. The transient negative lift associated with undergoing delayed advanced rotations totally disappeared case. A digital particle image velocimetry (DPIV) measurement middle stroke revealed slight difference vortical structures surrounding two terms proximity shed trailing-edge vortices (TEVs). Also, linearly twisted nature caused coherent leading-edge vortex (LEV) be stabilized throughout wingspan. increased radial limit stall from 3.6c 4.8c wing. In general, symmetric higher efficiency. corresponding net force vectors were tilted almost vertical direction comparison is indication natural adopt specific addition deformation upward titling vector, will significantly enhance performance.