CFD BASED SIMULATION OF CAMBER EFFECT OF FLAPPING WING WITH UNSYMMETRICAL STROKES DIHEDRAL ON POWER AND ENDURANCE EFFICIENCY

In the development of unmanned technology, Micro Aerial Vehicle (MAV) is quite a demanding breakthrough. Decreasing size of the vehicle requires a power that may be generated from flapping wing motion mimicking from the nature of flying animals such as birds. It is observed that birds mainly have very high cambered wings compared to aircraft wings. To measure its performance, required power and endurance efficiency becomes important parameters for the development of flapping wing motion for MAV. This thesis uses computational approach to study the camber effect on flapping motion. As a computational model, common swift bird is taken as a reference for wing properties, flapping characteristics, and flight condition. In addition, the kinematics is modelled to obtain flapping-twisting motion with unsymmetrical upstroke and downstroke dihedral to mimic the swift bird flight. The wing geometry is simplified to cambered plate with common swift half planform. For computational simulation of the flapping motion, computational model is treated as unsteady flow and using dynamic grids with a certain dense closed to the wing surface to capture viscous effect at low Reynords number of 2x 104. Multiblock structured mesh is chosen to accommodate the requirements for the physical phenomena and the mesh is arranged such that the grid does not intersect each other. The computational test matrix is applied to the solver and the solutions of aerodynamic forces, moment, and velocities are substituted in the equation to calculate the power. The curves of power consumption obtained are integrated to acquire the energy and endurance efficiency. The simulations are carried out with the variation of cambers in order to investigate its effect on the energy expense in each period. The camber is varied from non-cambered, 5%, 11%, 18%, until 25% of the chord. The maximum camber location is then varied as 10%, 20%, 30%, and 50% of the chord. The flapping frequency is around 9 Hz referring to the birdâ€™s characteristic. The motion is differed into two cases, zero twist and 10 degrees maximum twisting angle. The simulation results show that as the camber increases, the energy increases together with the endurance efficiency which lays between 22-35 percents, and it decreases as the optimum efficiency is reached at 11% cambered case. However, the maximum camber location has no such significant effect on the energy and efficiency. Also, the twisting motion considerably gives contribution on thrust compared with the motion without twisting.