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伴随优化方法在优化过程中不受设计变量个数的限制,有巨大的工程应用前景。基于非结构混合网格技术,采用雷诺平均Navier-Stokes方程、离散伴随优化方法以及自由形面变形(FFD)技术,建立了飞行器气动外形优化设计系统。离散伴随方程采用公式推导的方法直接获取,并运用LU-SGS迭代求解。通过与差分结果进行比较的方式,对通量的雅可比矩阵和目标函数敏感导数开展了确认,并对文中黏性通量项、限制器以及湍流黏性系数的近似处理方法做了分析对比,验证了近似处理方法的合理性和可行性。采用建立的优化系统,完成了ONERA M6机翼在跨声速条件下的减阻优化,并比较了有无容积约束下优化结果的差别。模拟验证结果表明,建立的飞行器气动外形优化设计系统具有较高的可靠性和有效性,可以用于三维飞行器外形的减阻优化。
With the optimization method in the optimization process is not limited by the number of design variables, there is a huge engineering application prospects. Based on the unstructured hybrid grid technique, the aerodynamic shape optimization design system of the aircraft is established using the Reynolds-averaged Navier-Stokes equation, the discretization concomitant optimization method and the freeform deformation (FFD) technique. Discrete adjoint equations are derived directly from the equations and LU-SGS iterative solutions are used. By comparing with the difference results, the Jacobian matrix of flux and the sensitive derivative of objective function are confirmed. The viscous flux term, limiter and turbulent viscous coefficient approximation method are compared and analyzed. The rationality and feasibility of the approximate processing method are verified. By using the optimized system, the drag reducing optimization of ONERA M6 wing under transonic condition was completed, and the difference of optimization result with and without volume constraint was compared. Simulation results show that the aerodynamic shape optimization design system of the aircraft has high reliability and effectiveness and can be used to reduce the drag of the three-dimensional aircraft.