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.