基于势流模型与等几何配点法的机翼翼型优化

Airfoil Optimization with Isogeometric Collocation Based on Potential Flow Model

基于空气动力性能数值计算的机翼翼型优化设计可以降低成本,缩短设计周期,已逐渐成为目前翼型设计的主要发展方向.因此,提出一种基于势流模型与等几何配点法的机翼翼型优化方法.利用等几何配点法对不可压缩理想来流下的势流模型求解速度势;结合叶素理论计算翼型的空气动力特性指标,即升阻比,构造包含最大升阻比和最小拟合项的目标函数,再运用多种最优化方法求解得到优化后翼型,同时保证了翼型的气动性能和外形的光顺性.通过渐进迭代逼近算法对3类翼型数据点拟合得到初始翼型的NURBS表示,对其优化结果表明,该方法不仅保持翼型的自身特点和光顺性,而且显著提升了升阻比.

The airfoil optimization design based on numerical calculation of aerodynamic performance can reduce the cost and shorten the design cycle,which has gradually become the mainstream of airfoil design.This paper presents an optimization method for airfoils based on the potential flow model utilizing the isogeometric collocation method.Firstly,the velocity potential of the potential flow model under an ideal incompressible flow is solved by using the isogeometric collocation method.Then,the airfoil’s aerodynamic characteristic index,e.g.,lift-to-drag ratio,is calculated based on the Blade Element Theory.Finally,an objective function is formulated to maximize the lift-to-drag ratio and minimize the fitting error.Various optimization methods are then employed to obtain airfoils optimized for both aerodynamic performance and shape smoothness.The NURBS representations of the initial airfoils are acquired by fitting the three types of airfoil data points by the Progressive Iterative Approximation method in the experiment,and the optimization results show that the proposed method not only maintains the airfoil's characteristics and smoothness,but also significantly improves the lift-to-drag ratio.