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基于非均匀有理B样条的自由型面变形(NFFD)技术具有对变形对象普适性和控制点影响区域局部性的特点,广泛应用于气动外形优化。本文通过扩展控制体和合理布置外侧控制点,实现了NFFD技术在参数化曲面并改变曲面形状时,同步变形控制体内的表面网格和空间网格,并从理论上保证了控制体边界内外的网格协调。基于离散伴随方法求取梯度,分别采用拟牛顿(QN)法和序列二次规划(SQP)优化方法,通过从初始翼型NACA0012到标准翼型EH1590的反设计,研究了NFFD控制点数量和分布对设计结果的影响。在某飞翼标模单点全机升阻比优化应用中,改进控制点分布后获得了更高的升阻比,收敛速度显著提高。
The free-form surface deformation (NFFD) technique based on non-uniform rational B-spline has the characteristics of regional generalization of deformation objects and control points, and is widely used in aerodynamic shape optimization. In this paper, by extending the control body and arranging the outer control points reasonably, the NFFD technique can synchronously deform and control the surface meshes and the spatial meshes of the body while parameterizing the surface and changing the shape of the curved surface, and theoretically guarantee the inner and outer Grid coordination. Based on the discrete adjoint method, the QN and SQP optimization methods were used respectively. The number and distribution of NFFD control points were studied by inverse design from initial airfoil NACA0012 to standard airfoil EH1590 Impact on design results. In single-point full-height lift-drag ratio optimization of a flying wing model, a higher lift-drag ratio is obtained after improving the control point distribution, and the convergence speed is significantly improved.