螺旋桨安装效应对无人机气动特性影响

为解决某型飞翼布局无人机(UAV)带动力构型风洞试验最大升阻比相对无动力状态大幅下降的问题,采用计算流体动力学(CFD)方法对无人机无动力与带动力构型进行了数值模拟,数值模拟结果分别与无动力以及带动力风洞试验数据吻合良好,在此基础上深入研究了螺旋桨安装效应对无人机气动特性的影响。结果表明:推力螺旋桨与机身之间气动干扰产生的低压区致使阻力增加,从而导致飞机最大升阻比相比无动力状态下降了30.7%。针对无人机在推力螺旋桨影响下出现的最大升阻比下降问题,采用增大螺旋桨与机身之间距离的方法可以有效地消除机身后部出现的低压区,减小了阻力,提升了无人机最大升阻比。桨毂拉长方案在8°和9°迎角下最大升阻比分别提升了17.3%和15.4%。

Impacts of propeller installation effect on aerodynamic performances for UAV

Computational fluid dynamic (CFD) approaches were implemented on prop-uninstalled and prop-installed configurations of a flying wing unmannel aerial vehicle (UAV), so as to solve the problem of the decline of the maximum lift-drag ratio, and the results obtained through numerical methods were shown to be in good agreement with the test data. The impacts of the installation of the propeller on the aerodynamic performances of the aircraft were studied in depth on the basis of the collaborative experiment and numerical research. Detailed analysis of the numerical results indicated that the lowest pressure areas at the aft part of the airframe generated by the aerodynamic interactions between the propeller blades and airframe led to the increase of the drag and hence a decrease of around 30.7% in maximum lift-drag ratio. The feasibility of center shaft extension can effectively reduce the lowest pressure areas at the aft part of the airframe and increase the maximum lift-drag ratio of the aircraft by 17.3% and 15.4% at the angles of attack of 8° and 9°, respectively.