基于熵产方法的跨音速翼型减阻优化设计

Entropy generation method for aerodynamic optimization design of transonic airfoil to drag minimization

将熵产方法引入跨音速翼型气动优化设计中,采用涡黏性模型对翼型流场熵产进行计算,进而阐述熵产对翼型阻力的影响.通过类别形状函数（CST）方法和径向基函数（RBFs）网格变形方法完成翼型参数化建模与网格变形,并将改进的NSGA2多目标遗传算法与CFD计算耦合起来实现了翼型自动优化设计,用此方法进行了跨音速翼型的气动优化设计,目标函数为来流马赫数为0.73、攻角为2.54°时升阻比最大,熵产最小.设计结果表明：优化方法在小种群下有很好的全局收敛性,得到的非支配解集分布均匀,质量较高.与参考翼型相比,优化翼型通过降低流场熵产,有效地减少了翼型阻力,大幅度提高了翼型升阻比,消除或减弱了翼型上表面激波,有效提高了翼型的气动性能.

Entropy generation method was applied into the transonic airfoil aerodynamic optimization design to demonstrate the impact of entropy generation on drag of airfoils. The eddy viscosity model was used to simulate the flow field and calculate the entropy generation rate.The airfoil automatic optimization design was realized by coupling the CST（class-shape function transform）parametric method and RBFs（radius basis functions） mesh deformation method with improved NSGAII（non-dominated sorting genetic algorithms II） multi-objective optimization and CFD（computational fluid dynamics） solver.This method was applied to the aerodynamic optimization design of transonic of airfoil, defining the lift-drag ratio and entropy generation rate as the objective functions,when Mach number is 0.73 and the angle of attack is 2.54°.The optimized results unfold that,the proposed method is capable of realizing better performance in practical aerodynamic optimization,with the features of strong global convergence under the small population.The non-dominate solution acquired evenly has quite pleasing quality,which can provide the designer a wider choosing space. Compared with the reference airfoil, the drag of the optimized airfoils are decreased by reducing the flow field entropy generation rate,which greatly improves the lift-drag ratio.The shock wave on the upper surface of optimized airfoils are eliminated or weakened which effectively improve the aerodynamic performance of the airfoil.