Calculation And Analysis Of Gust Response Of Flapping-wing Air Vehicle

In this paper by solving the unsteady N-S equations, numerical simulation is carried in flapping motion of NACA0012 airfoil, and the aerodynamic response of a flapping airfoil in continuous sinusoidal gusty condition is calculated based on field velocity method. The effects of gust fluctuation amplitude, frequency and airfoil kinematics are investigated.The finite-volume method based on Jameson cell-centered scheme with artificial dissipation is applied to solve the two-dimensional N-S equations transformed by preconditioning method, and the dual-time stepping for multistage schemes is used for time marching. Turbulence model is Detached eddy simulation (DES) model based on Spalat-Allmaras model. A method called elastic deformation is taken to form dynamic grid of flapping airfoil. Good agreement is observed between the numerical computations and the experimental results in terms of average thrust coefficient with different kinematics.The aerodynamic performance of a flapping airfoil in various gusty conditions is studied, and the responses under vertical and horizontal gust are calculated. Study shows that the flapping airfoil with certain kinematics can effectively alleviate the fluctuation of horizontal gust response, which means horizontal gust rarely affects the flapping response; aerodynamic response fluctuates a lot under the vertical gust. Also the effects of the parameters of horizontal and vertical gust to the flapping airfoil aerodynamic performance are calculated: the impacts of horizontal gust fluctuation amplitude and frequency act insignificant in gust response; when double the amplitude of vertical gust, so goes the response fluctuation. In the calculations of impacts of airfoil kinematics to gust response, no single parameter is solely responsible for capability to reduce the wind gust of flapping wing.