The Study On Aerodynamics And Optimization For Flapping-Wing MAV

With the rapid development of relevant technology such as micro electronics and MEMS, the Micro Aerial Vehicle (MAV) is becoming the hotspot in aircraft design for its characteristics of small size, light weight and excellent concealment. The flapping wing MAV which simulates the bird like flapping style is capable of yielding lift and thrust simultaneously and thereby elide propelling devices and certain control surfaces to simplify the structure and to lower weight, and this is a very suitable style for MAV.The flapping wing flight yields lift in a special way which is vastly different from traditional fixed wing theories. These days many researches on the high lift mechanism in bird or insect flapping flight have been carried out in home and abroad, and researchers do make progress on the studies focusing on the unsteady features of flapping wing flight by utilizing modern numerical methodsThe conventional Vortex Lattice Method is incompetent for the unsteady flow in flapping motion. By introducing the unsteady boundary conditions and improving wake model, an Unsteady Vortex Lattice Method (UVLM) program was implemented, which is suitable for the simulation of unsteady aerodynamics in flapping wing flight.The studies of flapping wing aerodynamics in the past seldom included the flexibility of the wing while in the real motion of flapping, the bird's wings may yields dramatic flex deformation in the effects of external aerodynamics and muscle control. Based on the traditional rigid flapping wing model, a new flapping wing model in which flex deformation and instantaneous shape velocity are included is proposed. Additionally the expressions of aerodynamics are improved to predict aerodynamic coefficients in higher precision.Furthermore, the influence of wake model on algorithm's real time performance is studied. The results show that with the precondition of maintaining certain precision, the savings in CPU time with wake vortex ignoring could be up to 2/3; by utilizing the parallel processing capability of GPU, the iteration on wake model is optimized, and the results show that the time savings could reach 3/4. These all indicate the important value of UVLM in the optimization of flapping wing vehicle design as a fast aerodynamics approximation method. Finally, in order to develop theoretical instructions for the design and prototype trail produce, by integrating the UVLM and Pattern Search method, the elementary optimization of geometry shape of flapping wing and the parameters of flapping motion model is studied, and the interpretations for the results from current theories are proposed.