小展弦比薄机翼精细化气动优化设计研究

Refined aerodynamic design optimization of a wing with small aspect ratio

战斗机类小展弦比薄机翼的气动设计,主要考虑机翼的平面形状以及弯扭和厚度修形设计,忽略了机翼翼型的精细化设计,因此气动分析手段一般采用Euler方程结合黏性阻力修正的方法.以某典型战斗机机翼为例,分别使用Euler和RANS方程对机翼的流场与气动特性进行了数值模拟,发现Euler方程无法精确捕捉附面层内的流场结构,证明传统使用的Euler方程已不能满足战斗机机翼精细化设计的需要.对该机翼的翼型进行了气动优化设计,发现翼型的设计对该小展弦比薄机翼会失效,证明这类机翼必须在三维环境下进行多剖面翼型设计.综合FFD参数化方法、稳健的动网格技术、Kriging代理模型和粒子群算法,构建了三维气动优化设计方法.利用该方法对该机翼三个剖面翼型进行了跨音速巡航状态单目标以及跨音速/超音速巡航状态多目标精细化化设计,优化设计后机翼的气动性能得到很大的提高.

For aerodynamic design of figher wings with the feature of small aspect ratio, the plat shape, camber-twist and thickness modification are mainly concerned and refined design of the airfoil is neglected. Therefore, Euler equation combined with boundary layer is the main technique to calculate the aerodynamic characteristics. Taking a typical fighter wing as an example, Euler equation and RANS equation are respectively utilized to calculate the flow field of the figher wing. From the result, the flow details cannot be captured by Euler equation which reveals that Euler equation is not qualified for refined design of figher wing. Airfoil aerodynamic design optimization is carried out and it is inferred that the results of airfoil design does not hold in small aspect ratio wing. Therefore for small aspect ratio wing, airfoil design optimization must be conducted in 3-D circumstance. A 3-D aerodynamic design optimization frame is built which consists of FFD parameterization method, robust mesh deformation technique, Kriging surrogate model and PSO optimization algorithm. Employing the optimization flame, a single objective design is carried out at transonic state and a multi objective design is conducted at transonic/supersonic states. Aerodynamic characteristics are greatly improved from the design results.