无轴涵道旋翼气动特性数值研究

采用基于非结构网格的滑移网格技术对无轴涵道旋翼与传统涵道旋翼的气动特性进行了非定常Euler方程数值模拟。分别考察了无轴涵道旋翼与传统涵道旋翼气动特性差异,中心孔径、涵道扩散角、涵道翼型对无轴涵道旋翼气动特性的影响。涵道扩散角变化范围为-6°~10°,涵道翼型选择NACA66、NACA0018及NACA4415三种翼型进行研究。研究发现:涵道翼型类型对无轴涵道旋翼的拉力分配影响较大,对称翼型能减弱旋翼上方低压涡从而涵道能产生更大的拉力；无轴涵道旋翼比传统涵道旋翼具有更优的拉力性能,转速为18 000 r/min时其总拉力是后者的1.185倍；减小无轴涵道旋翼的中心孔径能提高总拉力值,但整体耗能也将随之提高；涵道拉力占比越高的翼型,其最佳涵道扩散角越大,该状态下涵道拉力占比最高。 

Numerical research on aerodynamic characteristics of shaftless ducted rotor

The unsteady Euler equations for the aerodynamic characteristics of shaftless and traditional ducted rotors were numerically simulated by using the sliding mesh technique based on unstructured meshes. The difference of aerodynamic characteristics between shaftless ducted rotor and traditional ducted rotor was investigated. The effects of center aperture, ducted diffusion angle and ducted airfoil on the aerodynamic characteristics of ducted shaftless rotor were studied. The divergence angle of the ducted rotor ranged from -6°—10°. The ducted airfoils were NACA66, NACA0018 and NACA4415. It was found that the type of ducted airfoil had a great influence on the tension distribution of the shaftless ducted rotor, and the symmetrical airfoil can weaken the low-pressure vortices above the rotor so that the ducted rotor can produce greater tension; the shaftless ducted rotor had better tension performance than the traditional ducted rotor, and its total tension was 1.185 times of the latter when the rotational speed was 18 000 r/min; reducing the central aperture of the shaftless ducted rotor can improve the total tension value, however, the overall energy consumption also increased; the higher proportion of ducted tension means the larger optimal ducted diffusion angle, and the highest proportion of ducted tension in this state.