新型宽体客机以更高马赫数进行跨声速巡航，且采用大量超轻复合材料以及更大的展弦比设计，导致气动和结构耦合的气动弹性效应愈加明显，并由此导致了一系列不同于传统民用飞机的设计问题，包括无法采用简化的气动力分析方法及各部门、学科间交替迭代的解耦设计思路等。多学科优化设计方法在一定程度上提供了新的设计思路和技术支持，但应用于宽体客机设计，仍存在计算耗费大、设计时间长的问题，其在飞行器设计中的应用也大多只关注单一学科、单一设计点或单一目标。对于洲际航程的宽体客机，载油量可达自重的20%，整个航行过程中由于耗油自重不断减小，导致气动性能也在不断变化，是一个典型的多学科耦合、多设计点优化问题。另外，飞行器设计中的各种不确定性因素严重影响系统的可靠性，传统确定性设计难以适应未来发展需求，需进行鲁棒优化设计。因此，发展适合于宽体客机、更贴近工程实际的高效多学科综合优化设计方法是非常有必要的。本文围绕该问题主要进行了以下研究：

    1) 采用基于RANS方程的CFD计算方法实现了对复杂跨声速流场的高保真度计算；在CFD求解器中两方程k-w模型基础上增加了显式代数应力模型，对F6标准模型进行了计算，并通过与实验结果对比，验证了该气动计算方法的有效性和精度。发展了基于CFD/CSD耦合的高保真度气动弹性分析方法，通过对AGARD 445.6机翼和某宽体客机模型进行计算分别验证了耦合方法在动气动弹性和静气动弹性计算方面的效果。

    2) 建立了基于代理模型的全局优化设计体系。针对气动外形优化，建立了适合不同问题的几何参数化方法，并基于RBF插值构建了气动网格自动化建模工具；基于智能全局粒子群优化算法，进行了单目标、多目标及参数自适应改进。以Kriging模型为中心，研究了逐步提高代理模型精度的加点准则，以及通过最小角回归算法选择泛Kriging模型趋势函数的代理模型构建方法。通过分析一系列数值算例和二维翼型优化算例，对比验证了以上各方法的性能。

    3) 发展了二维翼型的区间不确定性分析及鲁棒优化设计方法。对于二维翼型跨声速气动问题，采用基于最大、最小优化的非线性区间不确定性分析方法，分别对考虑几何不确定性和飞行参数不确定性的阻力性能进行了定量的不确定分析。对于考虑区间不确定性的一般鲁棒优化设计问题，通过区间序关系及区间可能度模型对不确定目标函数和约束进行变换，建立等价的多目标确定性优化问题。以超临界翼型标准优化算例为例，分别考虑几何和飞行参数不确定性，进行了鲁棒优化设计，并与确定性优化设计结果进行了对比，结果表明，鲁棒优化设计得到的最优阻力系数虽大于确定性优化设计结果，但相对不确定性因素的鲁棒性更强。

    4) 开展了三维宽体客机综合优化设计研究，建立了静气弹/气动/结构综合优化流程/变量/目标/约束体系。确定了以全飞行任务剖面总油耗为目标的气动外形/结构综合优化设计模型，包括气动外形、布局及结构尺寸设计变量，以及航程、变形、升力等约束。以简化宽体客机模型（翼身组合体模型）的地面型架外形为支撑，采用高精度气动弹性耦合计算方法计算主飞行任务剖面内各设计点的飞行外形，并进行相应的总油耗、气动力、重量及结构变形等性能分析，获得目标函数及约束函数值。通过基于代理模型的优化设计方法对上述问题进行求解，获得了较初始气动外形和结构配置综合性能更优的设计方案。

    New wide-body jet cruises at a higher Mach number, and uses a lot of composite materials and a larger aspect ratio. As a result, the aeroelastic effect becomes more and more obvious, which leads to a series of design problems different from traditional civil aircraft, including the inability to adopt simplified aerodynamic analysis methods and the decoupling design of alternating iterations among departments and disciplines. Multidisciplinary design optimization provides a new design concept and technical support, but it still has the problems of high computational cost and difficulty in solving when applied to the wide-body aircraft design. And most of its applications in aircraft design only focus on a single discipline, a single design point or a single goal. However, for a wide-body jet with intercontinental flight, the fuel load can reach 20% of its deadweight. During the whole flight, the deadweight is constantly reduced due to the fuel consumption and the aerodynamic performance is also constantly changing. It is a typical multi-disciplinary coupling and multi-design point optimization problem. In addition, various uncertain factors seriously affect the reliability of the aircraft system, and the traditional deterministic design is difficult to meet the needs of future development, so robust optimization design is needed. Therefore, it is very necessary to develop efficient multi-disciplinary comprehensive optimization design method which is suitable for wide-body aircraft. Focusing on the above issues, the research progress of this paper is as follows:

    1) High fidelity simulation for transonic complex flowfield is achieved by CFD method based on RANS equation, and the explicit algebraic stress model is added to the two-equation k-w model in the CFD solver. The validity and accuracy of the proposed method are verified by comparing the calculation results of F6 model with the experimental results. A high fidelity aeroelastic analysis method based on the CFD/CSD coupling is established. The effectiveness of the coupling method in flutter and static aeroelastic calculations is verified by the simulation of the AGARD 445.6 model and a wide-body jet model, respectively.

    2) A global optimization design process based on surrogate model is established. First, for aerodynamic shape optimization, geometric parameterization methods suitable for different problems are introduced, and an improved automatic modeling tool for aerodynamic grid is constructed based on RBF interpolation. Second, based on the intelligent global particle swarm optimization algorithm, single-objective, multi-objective and parameter adaptive improvement are carried out. Third, using Kriging model as the surrogate model, the infill criterion to improve the accuracy of Ordinary-Kriging model and the method of selecting the basis trend function of Universal-Kriging model by Least Angle Regression algorithm are studied. The performance of the above methods is verified by a series of numerical examples and the two-dimensional supercritical airfoil optimization example.

    3) The interval analysis of uncertainties and robust optimization design method for airfoils are established. For transonic aerodynamic problems of airfoils, the nonlinear interval analysis method based on maximum and minimum optimization is used to quantitatively analyze the drag considering geometric uncertainties and flight parameter uncertainties. For robust optimization design problems with interval uncertainties, an equivalent multi-objective deterministic optimization problem is established by transforming uncertain objective function through order relation of interval number and uncertain constraints through possibility degree of interval number. Also taking the supercritical airfoil optimization as an example, the robust optimizations considering geometric and flight parameter uncertainties are carried out, and the results are compared with those of deterministic optimization. The results show that the optimal drag coefficient obtained by robust optimization is larger than that of deterministic optimization but has better robustness.

    4) The integrated optimization design of three-dimensional wide-body jet is studied and the variables/objective/constraint system of static aeroelastic/aerodynamic/structure comprehensive optimization is established. The optimization problem with the total fuel consumption of the whole main flight mission profile as the goal was determined, including design variables of aerodynamic shape, layout and structure size, and constraints of range, deformation, lift, etc. Based on the Jig shape of simplified wide-body jet model (wing-body combination model), the flight or cruise shapes of each design point in the main flight mission profile are calculated by high precision CFD/CSD coupling method, and the corresponding total fuel consumption, aerodynamic force, weight and structural deformation are analyzed to obtain the objective and constraint function values. The optimization design method based on surrogate model is used to solve the above problem, and a design scheme with better comprehensive performance than the initial model is obtained.