翼上螺旋桨构型耦合气动特性及翼型优化设计

针对半环形式翼上螺旋桨构型，研究了螺旋桨-机翼耦合流场特性，并以短距起降（STOL）状态最优升阻特性为目标对机翼翼型进行全局优化。首先，针对螺旋桨-气动面耦合构型，通过动量源法与真实桨叶模型CFD的计算对比，分析动量源法用于该构型设计分析的可行性。其次，为得到有利于桨-翼耦合特征的新翼型，建立了翼上螺旋桨构型自由型面变形（FFD）参数化模型，采用遗传算法对翼上螺旋桨构型机翼翼型进行全局寻优设计，分析了优化翼型参数及流场变化规律。最后，将优化翼型用于三维半环形机翼，分析其流场特性与二维计算结果的异同，验证二维翼型优化的有效性。结果表明：真实桨叶多重参考系（MRF）方法不能准确计算翼上螺旋桨构型下的流场结构，而动量源法计算结果与真实桨叶滑移网格非定常方法较为吻合；采用二维动量源CFD方法进行翼型的遗传算法优化是有效的，受半涵道的保护，二维优化翼型的优势在三维构型中得到了有效继承；翼上螺旋桨构型的翼型优化应当着重关注翼面曲率变化，在本文计算状态下，通过增加桨盘附近翼面曲率、保持附着流动来加强Coanda效应，有效实现了气动增升，优化后机翼升力提高了22.51%，显著减弱桨盘后高压区并产生二次吸力峰值，同时保持了机翼负阻力特性。

Coupled aerodynamic analysis and airfoil optimization design for over-wing propeller configuration

This paper studies the characteristics of the propeller-wing coupled flow field of the channel wing configuration. It also carries out an airfoil optimization with the aim to improve the lift efficiency at Short Takeoff and Landing (STOL) condition. By adopting the momentum source method and carrying out the real blade model CFD analysis of the propeller-wing interaction flow field, this paper first analyzes the feasibility of the momentum source method for the design. Then, to obtain a new airfoil with coupled aerodynamic features, an parameterized model with Free-Form Deformation (FFD) method is established to optimize the airfoil of the channel wing, and the changes of optimal airfoil parameters and the flow field are analyzed. In the end, the CFD analysis for three dimensional channel wing is carried out to compare and verify the two-dimensional airfoil optimization results. The results show that the Multiple Reference Frame (MRF) method cannot correctly analyze the flow field of over-the-wing propeller, while the momentum source method is more consistent with the unsteady sliding mesh method. The genetic algorithm optimization using the two-dimensional momentum source CFD method is effective. With the protection of the half-duct, the advantages of two-dimensional optimization airfoil have been effectively inherited in the three-dimensional configuration. The airfoil design for channel wing configuration should focus on the curvature variation of the wing surface. In this paper, the Coanda effect is enhanced by increasing the curvature of the airfoil near the propeller and maintaining the attached flow, which achieved aerodynamic lift-increase. The lift of the optimal channel wing increases by 22.51%, and the high pressure area is significantly reduced behind the propeller and second peaks of suction appears, while drag is still negative.