This paper reports research efforts carried out by the DLR within the framework of the European Commission "Clean Sky" Joint Technology Initiative (JTI) to reduce the aerodynamic drag of helicopters via the application of streamlined hub fairings. A number of three-dimensional RANS simulations of the flow past the GRC common platform fuselage using baseline hub and different generic full fairing shapes were carried out with the unstructured finite volume DLR solver TAU. The computations simulated forward flight at Mach number = 0.204 and an angle of attack ranging between -15° and 15°. Chimera overlapping grid method was used to transfer the solution between the fuselage and rotor hub grids, while Wilcox's k-ω two-equation model was employed to simulate the effects of turbulence. The results revealed significant contribution of blade attachments and stubs to hub drag. An overall drag reduction of 17-19% could be obtained by proper optimization of the fairing, blade attachments and stubs.
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机译：本文报告了DLR在欧盟委员会“清洁天空”联合技术倡议（JTI）框架内进行的研究努力，通过应用流线型的集线器公平来减少直升机的空气动力学阻力。通过非结构化的有限卷DLR Solver Tau进行了许多使用基线枢纽和不同通用全面整理形状的GRC常用平台机身的三维RAN模拟。计算在Mach Number = 0.204处模拟前向飞行，并且在-15°和15°之间的攻角范围。嵌合体重叠电网方法用于在机身和转子轮毂网之间传递溶液，而使用Wilcox的K-ω两方程模型来模拟湍流的影响。结果揭示了刀片附件和短管对集线器的显着贡献。通过适当优化整流罩，刀片附件和存根，可以获得17-19％的总阻力减少。
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