Research On The Aerodynamic Characteristics And Structure Of A Bionic Flapping-wing Aircraft

Flapping wing aircraft has the characteristics of strong adaptability,good concealment and high flight efficiency.It has certain strategic significance in military development and great practical value and economic potential in civil use.In the research field of flapping wing aircraft,mechanical design and aerodynamic characteristics are two important research points,but there are still many problems to be solved.The research work of this paper is mainly based on these two research points.The flapping mechanism of flight vehicle is the core part,in order to determine the flapping mechanism and flapping function,analyzed and selected flapping mechanism.According to the movement characteristics of four bar linkage,the mechanical was designed,and the movement of the mechanism was simulated,which obtained the flapping mechanism motion curve.Then the curve of movement was fitted,with summing up the general form of this flapping motion function.The general form of the function is consistent with the flapping function of birds observed by other scholars,indicating the applicability of the four-bar linkage as flapping mechanism.The aerodynamic characteristics of the rigid wing of flapping wing aircraft are the basis of its flight mechanics research.In order to study the aerodynamic characteristics of the rigid wing,the pigeon wing was taken as the bionic object,the wing was modeled.Then the dynamic grid technology of Fluent was used to conduct numerical calculation of the flapping process of the rigid wing,and the rise resistance coefficient curve of the rigid wing was obtained.In addition,the characteristics of lift resistance of rigid fins at different angles of attack,frequencies and amplitudes are studied,and the relevant conclusions are given.The aerodynamic characteristics of flexible wing of flapping wing aircraft are the core of its flight mechanics research.In order to study the factors influencing the aerodynamic characteristics of flexible wings,four kinds of flexible wings were modeled,and the bidirectional fluid-solid coupling technology was used for numerical calculation.By comparing the lift resistance curves of flexible wings with rigid wings,the fluctuation time domain characteristics and peak value characteristics of flexible wings with large deformation are found,and the causes of the characteristics are analyzed.Finally,in order to prove the practicality of the characteristics of the fluctuation time domain,a high-speed photography experiment was designed to analyze the changes of wings during the flutter of pigeons.The analysis showed that pigeons could use the fluctuation time domain more flexibly,and proved the importance of the fluctuation time domain in the flapping of flexible wings.