A three-dimensional flapping wing mechanism for wind tunnel experiments

For the experimental study about aerodynamic characteristics of flapping wings,especially the unsteady flow at low Reynolds number, a kind of flapping wing mechanism which could achieve complex insect or bird wing kinematics was developed. The design is based on two dual-differential four-bar mechanism and the movement of the wings revolving around 3 axes can be controlled separately. Force and moment measurements were obtained from six-component transducers which are fixed at the root of each wing. A set of control-measure software based on LabVIEW was developed. By accurately control of six brushless motors with this software,different kinds of composite movements can be carried into effect on the wings. The wing with skin and the wing without skin were flapped at the same frequency and kinematics and the two resultant forces were subtracted in order to get the pure aerodynamic forces. The single degree-of-freedom (DOF) and three degrees-of-freedom flapping experiments are conducted in the opening section of a wind tunnel. The aerodynamic forces are compared. The results show that this system is suitable for the future comprehensive wind tunnel experiments to develop high efficient flapping wing and wing kinemics.