飞机在富含过冷水滴的环境中飞行会可能造成升力面结冰，使得流线外形被彻底破坏，诱发流动分离，进而导致升力下降，阻力增加，操稳特性急剧恶化，失速攻角大幅降低，严重的则造成机毁人亡。传统的机翼设计重点关注在巡航高度、巡航速度的性能，同时关注低速性能来保障起降过程，但是上述设计体系产出的机翼结冰后气动特性会大幅下降，因而严重依赖防（除）冰系统的保护。本文所进行的容冰设计意在机翼设计初期就考虑结冰的影响，通过翼型优化设计以及增升装置缝道参数设计最大限度地减小带冰后的气动性能损失，从而减轻结冰适航审定压力、提高飞行安全性。本文搭建机翼容冰优化设计平台，实现了准确预测带冰后气动特性，实现了飞机结冰过程数值模拟。开展了跨声速超临界机翼和低速无人机机翼容冰优化，重点解决了三个关键问题：第一，发展预测带冰大分离流动的湍流模型，完善对带冰失速特性的评估。通过引入模型ω破坏项的修正，改进了模型对分离剪切层中湍流非平衡特性的预测，发展了带分离修正的SPF k-(v^2 ) ?-ω和SPF k-ω两个涡粘性模型，其中SPF模型在预测附着流中的效果与现有模型相当，而预测带冰失速特性时相对现有模型有很大的提高，对不同冰型预测的最大升力系数误差在5%以内。第二，开发结冰计算模块，实现三维复杂构型结冰过程分析。改进Myers模型壁面温度取法，将Messinger计算的壁面温度作为其边界，避免了Myers模型使用的经验性，采用新发展的SPF k-v2-ω湍流模型计算空气流场部分，提高了结冰预测的精度。第三，提出多目标、多设计点的容冰优化策略，提炼容冰优化设计规律。改进CST参数化方法，提高了对翼型头部的精细化造型能力。开展多轮容冰优化，发现巡航+容冰的双目标优化的效率高。考虑结冰工况的不确定性，在优化中引入混沌多项式展开方法描述结冰工况变量的随机分布，进一步提高翼型容冰鲁棒性，发现不确定性优化既优化了翼型也同时改善了冰形。采用上述容冰优化设计体系优化出的容冰超临界机翼经风洞试验，其最大升力系数相对原始机翼提高了8.8%，最大升力系数对应失速攻角推迟4°，达到了巡航与容冰性能的兼顾。本文所发展的湍流模型、结冰计算软件以及容冰优化体系在机翼容冰设计中得到了检验，具有较高的工程应用价值。
Ice accretion poses threats to aircraft safety in natural icing conditions as it leads to lift reduction and loss of control. When aircraft pass through the environment containing supercooled water droplets, the lifting surface may suffer ice accretion. Optimization methods have been widely implemented in airfoil and wing design. The original design process of a wing with the multi-point/multi-objective optimization strategy is to reduce the aerodynamic drag. However, few optimization methods have been reported for the design of a practical airfoil and high-lift configuration considering the ice-accretion effects. In this research, the optimization of a wing with respect to ice-accretion effects has been studied. Modifications of turbulence models are proposed to accurately predict iced aerodynamics. Numerical simulation of the ice-accretion process is implemented to analyze the ice shape. The optimization of the ice-tolerable wing is studied based on the supercritical wing platform and unmanned aerial vehicle platform. Three main research have been done.The first research focuses on the turbulence model in predicting the large separation flow, especially the stall performance of the iced wing. By modifying the destruction term of ω-equation, the characteristic of non-equilibrium of turbulence in the separating shear layer region is improved. Two modified turbulence models are proposed, namely the separating shear layer fixes (SPF) models, SPF k-(v^2 ) ?-ω and the SPF k-ω. The separating shear layer fixes do not affect the original models when predicting the attached flow, while greatly help improve the models’ performance in predicting the stall state. Using the SPF modifications, the predicted maximum lift coefficient error is within 5%. The second research focuses on the simulation of the three-dimensional ice-accretion process. The Myers model’s temperature boundary is improved. By employing the wall temperature evaluated by the Messinger model, the generality of the Myers model is improved. With the SPF k-v2-ω model, the accuracy of the predicted ice shape is promoted. The third research point is the optimization of an airfoil with respect to the ice-accretion effect. The optimization strategies and tools are proposed to raise optimized efficiency. A leading-edge stressed class shape transformation (CST) method is used to parameterize the airfoil geometry. The iced performance is to some extent consistent with clean airfoil’s low-speed performance. The optimization considering only dual-objectives on the high-speed and ice-accretion points can efficiently obtain satisfactory designs. A technique of polynomial chaos expansion is used to propagate the input uncertainty through the deterministic system. The numerical results show that the multi-point/multi-objective optimization strategy can efficiently improve both the ice tolerance ability and the cruise performance of an airfoil. The reason for the revenue of the robust optimization is that the ice angle of the optimized airfoil becomes less critical to the incoming flow. The optimized ice-tolerable wing is tested in a wind tunnel experiment. Compared with the original iced wing, the maximum lift coefficient and stall angle of the ice-tolerable wing is increased by 8.8% and 4 degrees respectively.This paper develops the turbulence model for evaluating the iced performance, the method of predicting the ice-accretion process, and the optimization system of the ice-tolerable wing. Results show that the optimized wing is satisfied and developed methods have high engineering application value.
