Aerodynamic Analysis And Uncertainty Optimization Design Of Flapping-wing Micro Air Vehicle

Flapping-wing micro air vehicle(FWMAV),as a micro-complicated electromechanical system that simulates the functions of flying organisms,comes from the simulation of the movement of flying organisms in nature.Thanks to the high flexibility,high concealment,high bionic performance,and high miniaturization of the FWMAV,it plays a key role in the military and civilian fields.Its applications include disaster monitoring,environmental monitoring,search and rescue,border reconnaissance and battlefield reconnaissance,etc.The research and development of the FWMAV are on the ascendant,and the breakthrough of its key technology has important innovation significance.It is expected to promote the development of the entire unmanned air vehicle technology and break the technical barriers.In the research and development process of the FWMAV,how to achieve high-stability bionic flight under the interference of various uncertain factors is a key problem faced by domestic and foreign researchers.The core indicator of the FWMAV is the aerodynamic performance of the bionic flexible wings.Therefore,this dissertation takes the FWMAV as the research object,carries out the design and performance analysis of the multi-attitude flapping-wing mechanism and the bionic wing,and proposes a novel fluid-solid coupling numerical model and wind tunnel experiment system for the aerodynamic analysis of the bionic flexible wings.Combined with reliability analysis,aerodynamic uncertainty optimization design is carried out to improve the flight stability and endurance time of the FWMAV.The innovative research content of this dissertation mainly includes:(1)A multi-attitude mechanism design for the FWMAV is proposed.Based on the analysis of the flapping wing attitude motion of flying creatures in nature,the multi-attitude mechanism design of the FWMAV is carried out.Firstly,a design concept of the FWMAV based on a multi-attitude flight control mechanism is proposed,which improves the flexibility and controllability of the aircraft in the process of pitching,yawing,and rolling;Secondly,the bionic flexible wings is designed based on the characteristics of biological wings;Finally,according to the principle of bionics,the size and motion parameters of the aircraft are determined,and the kinematic performance simulation is completed.The multi-attitude mechanism strategy aims to provide theoretical guidance and practical application schemes for the maneuverable design of FWMAV.(2)A fluid-structure interaction numerical simulation model for the FWMAV is proposed.To analyze the aerodynamic characteristics of flexible wings in the FWMAV,a fluidstructure interaction numerical simulation model based on the combination of smoothed particle hydrodynamics and the discrete element method is proposed.Firstly,a threedimensional model of the flexible wing is created using a quasi-flexible concept.Then,the fluid domain is modeled using the smoothed particle hydrodynamics,while the structural solid domain is modeled using the discrete element method,and a fluid-solid interface algorithm is developed.Finally,research on parallel acceleration schemes is conducted based on graphical processing units.The construction of the numerical simulation model provides a theoretical basis for the optimization design of the FWMAV.(3)An experimental system and analysis method for the FWMAV is proposed.To carry out comprehensive and systematic research on the unique aerodynamic force and flow field structure of the FWMAV,a set of wind tunnel experiment systems and analysis methods is proposed.Firstly,a comprehensive wind tunnel experiment platform for FWMAV is built by using particle image velocimetry technology,which can collect mechanical and flow field structure data during flight;then,a flow field image reconstruction method based on the Kriging model is proposed to clearly describe the evolution process of the flow field structure,and the verification of the numerical and experimental models is completed;Finally,the uncertainty of the key parameters in the flight state is quantified using the wind tunnel experimental system.The proposal of a targeted wind tunnel experiment system and analysis method provides an experimental basis for in-depth exploration of the potential high-lift mechanism in flapping wing dynamics and also provides data support for the uncertain optimization design.(4)An aerodynamic performance analysis method for the FWMAV is proposed.To enhance the aerodynamic performance of FWMAV,research on the analysis of their aerodynamic characteristics is carried out.Based on the proposed numerical simulation and experimental models,the effects of lift,thrust,lift-to-power consumption ratio,and various dimensionless parameters are analyzed,and the flow structure of the flow field is comprehensively analyzed.The unsteady mechanisms of flapping are summarized and expanded,providing model and data inputs for optimization design.(5)An aerodynamic reliability-based design and optimization method for the FWMAV is proposed.To improve the stability and aerodynamic efficiency of the flapping-wing flight of the FWMAV,an optimization design method for the aerodynamic reliability of the FWMAV is proposed.Firstly,the aerodynamic performance function based on the accelerated Kriging surrogate model is established,and the point-adding strategy is optimized by adding a moving searching window;then,the reliability optimization of multiple design variables is carried out by using the improved particle swarm optimization algorithm.The optimized design of aerodynamic reliability has successfully realized the improvement of the endurance time and stable flight capability.