| With the development of the transportation industry and the importance of environmental protection,aeronautical research institutions around the world are demanding higher aerodynamic performance and aerodynamic noise performance of airfoils.The use of bionics to improve the performance of airfoil by applying some structures of nature’s living creatures can achieve higher performance and expand the scope of application as propulsion and control machinery.The SBD(Simulation Based Design)technique,a combination of optimization and CFD techniques,is an advanced goal-driven optimization method that has been applied in several design fields with significant results.In this paper,the SBD technique is introduced into the field of bionic wing design,focusing on the parametric deformation design of the leading edge concave-convex structure of the humpback whale leading fin and the parametric deformation design of the trailing edge serrated structure of the owl-like fin of the 3D wing,combined with the CFD numerical prediction method to evaluate the aerodynamic performance and aerodynamic noise performance.The total sound pressure level and peak sound pressure level are used as the targets.Under the guidance of the optimization algorithm,a multi-objective performance optimization design platform based on SBD technology is constructed for the bionic wing.First,the bionic design of the standard wing parameterization is carried out.Inspired by the concave-convex structure of the leading edge of humpback whale fin,a multi-segment exponential decay curve fitting is used to parametrically control the deformation;inspired by the serrated structure of owl fin trailing edge,the parametric deformation of the trailing edge of the wing is carried out by constructing two cutting-type tools of flat type and pointed tip type.Subsequently,the 3D airfoil with leading-edge concave-convex design is used as the object,and the numerical prediction with stall angle and maximum lift coefficient as the design objectives is completed by CFD viscous flow method,and the optimization algorithm combining fast non-dominated genetic algorithm and Kriging agent model is applied to carry out the multi-objective optimization design of the aerodynamic performance of the 3D bionic leading-edge concave-convex airfoil,and several design solutions with better aerodynamic performance are obtained.The improvement of stall angle in the design solutions is 33.3%and 16.7%,and the biggest improvement of lift coefficient of the four optimal individuals reaches 3.9%.The target functions of stall angle and lift coefficient have the highest correlation with the decay parameters of the exponential decay fitting curve,which proves the effectiveness of the decay characteristics of the exponential decay curve differing from the previous standard function curve for improving the aerodynamic performance.Then,the total sound pressure level and peak sound pressure level are determined as the noise optimization design objectives for the two trailing edge sawtooth bionic design 3D wings.A fast non-dominated genetic algorithm is selected to carry out the aerodynamic noise optimization design of the 3D trailing edge serrated wing,and the two individuals with the best aerodynamic noise performance are obtained.The total sound pressure level of the best individual is reduced by 9.41 d B,and the peak sound pressure level is reduced by about 7.98 d B.The sound pressure level spectrum,one-third octave curve and other acoustic characteristics of the aerodynamic noise of the standard wing and the optimized wing are compared and analyzed.The flow mechanism of the optimized three-dimensional bionic trailing edge sawtooth deformed airfoil is studied.The above two bionic airfoil performance optimization platforms demonstrate the feasibility and potential of SBD technology for the optimized design study of bionic airfoil aerodynamic performance and aerodynamic noise. |
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