A computational model of flexible, flapping membrane wings in quasi-steady, laminar flow (computational fluid dynamics)

To date, many computer models of membrane wings have been developed; but these either model nonflapping, elastic membranes or flapping, rigid membranes. This project attempted to combine these two aspects; to model a flapping wing composed of an elastic membrane.; The wings considered consist of a rigid leading edge spar and fixed wing root between which a membrane is stretched. Ribs running perpendicular to the spar can also be present. A strip model is used and classical thin-airfoil theory predicts the aerodynamic forces present. The airflow is assumed to be incompressible and quasi-steady, and inertial reaction forces in the spar are ignored. An iterative solution is used to find the membrane shape by which the aerodynamic forces affect the shape and the shape affects the aero-forces.; The results of the model compare well with wind tunnel data in terms of average wing lift for flight velocities from 10 to 10 m/s. The comparison was less encouraging for average wing thrust and lift over the flap cycle. The presence of one or two evenly spaced ribs improved thrust and lift, and allowing more slack, up to a point, also seemed to improve thrust and lift.