地面效应中悬停旋翼的自由尾迹计算

 发展了一种具有良好收敛性的自由尾迹模型,用于对地面效应(IGE)状态下的旋翼悬停尾迹进行数值模拟。其中使用直涡元对桨尖涡丝进行离散,使用面元法模拟地面对流场的影响。针对以往类似研究中旋翼高度较低时自由尾迹迭代不易收敛的问题,引入了地下尾迹等比例修正并提出了环式地面面元分布等多项修改办法来改善计算模型的收敛性,同时这些改进也起到了削减计算量的作用。为了对新构建模型进行验证,以多个高度下的旋翼有地效状态为算例,对其尾迹几何结构进行了计算并与实验值进行了对比,结果显示二者符合得较好,证实了该模型具有较高的准确性。

Free-wake Analysis of Hovering Rotor in Ground Effect

A free-wake based model with fine convergence is developed to predict the wake geometry of a hovering rotor operating in ground effect (IGE). The vortex line is discretized into straight-line filaments, and the influence of the ground is modeled using a surface panel method. Since earlier studies show it is hard for the free-wake to converge when the rotor is hovering at a low height, the work of this study incorporates several modification measures to improve the convergence of the model, such as rectifying the wake vortices below the ground plane proportionally and distributing the ground panels circularly, which reduced the calculation amount of the model at the same time. The model is validated with prediction instances in which the rotor is placed at different heights. A comparison of the determined wake geometries with experimental data shows good agreement and proves the proposed model possesses good accuracy.