Aerodynamic Performance Analysis And Optimization Design Of Low Reynolds Number Wind Turbine Airfoil

Wind power generation technology is a clean,pollution-free renewable energy utilization technology.In recent years,the research on small and medium sized wind turbine is more and more concerned by scholars all over the world.The blade is one of the key components of the wind turbine to obtain wind energy,and its aerodynamic performance mainly determines the wind energy utilization and load characteristics of the wind turbine.Because the small wind turbine blade Reynolds number range is low(usually the Reynolds number is less than 5×105),the flow velocity of the airfoil surface boundary layer is often in the laminar flow state,the anti-back pressure gradient ability is weak,it is easy to produce the flow separation prematurely,which has a serious impact on the aerodynamic performance of the airfoil.Therefore,the flow separation,aerodynamic characteristics analysis and optimization design of the blade airfoil at low Reynolds number of 1×105~5×105 are carried out in this paper,the main contents are as follows:1.Based on the RANS equation and the modified transition model,the numerical model of the aerodynamic characteristics of the low-Reynolds number wind turbine airfoil is established,and the applicability of the numerical methods is verified by comparing the results of different turbulence models with the experimental results.The airfoil aerodynamic characteristics of multi-Reynolds number and multi-angle are studied under the condition of low Reynolds number.Based on the analysis of the flow separation and transition of the airfoil surface,the variation of transition positions of the upper and lower airfoil is obtained;The formation of laminar separation bubble and its effect on aerodynamic performance of airfoil at low Reynolds number are analyzed.2.Through the research on the laminar separation bubble formation mechanism of low Reynolds number airfoil,the influence of the geometrical characteristics with different positions,shapes and sizes on the aerodynamic performance and flow loss characteristics of low-Reynolds number airfoil is analyzed.The formation mechanism of laminar bubble at low Reynolds number is revealed,and the influence of surface geometrical characteristics on aerodynamic performance is obtained.3.Based on the improved Hicks-Henne function,the parametric mathematical model of the airfoil geometry of the wind turbine is established.The design space of the airfoil family is obtained by the Latin hypercube test design method.The Kriging agent model,the genetic algorithm and the NSGA-? optimization algorithm are used to couple Low-Reynolds numberairfoil flow field analysis.Taking the maximum lift-drag ratio of single-mode and multi-mode aerodynamic performance parameters as the goal,the single-objective and multi-objective aerodynamic optimization research of low Reynolds number airfoil considering transition are carried out.A low-Reynolds number wind turbine airfoil aerodynamic optimization design method is proposed,which provides an important reference for the development and application of low speed small wind turbine airfoil.