This paper presents a collaborative experimental and numerical research to investigate the influences of the installation of propeller on aircraft aerodynamic performance, and two approaches to mitigate the propeller installation effect are also analyzed. The configuration under investigation is based on a real flying wing unmanned aerial vehicle with a two-bladed pusher-propeller mounted on the aft part of its associated airframe. Reynolds-averaged Navier Stokes simulations coupled with a structured finite-volume cell-vertex based solver are applied to propeller uninstalled and installed configurations, and the numerical results are shown to be in good agreement with the experimental data. The comparative results obtained through prop-uninstalled and prop-installed cases show that the installation of the pusher-propeller leads to the decline of the maximum lift-drag ratio due to aerodynamic interactions between the propeller and airframe. Detailed analysis of the numerical results highlighted that the low pressure areas on the aft part of the airframe generated by the installation of the pusher-propeller will result in an increase of the base drag and hence a decline of the maximum lift-drag ratio. The feasibilities of center shaft extension and the modification of airframe geometry to mitigate the propeller installation effect are verified by numerical simulations, and results showed that proper propeller–airframe spacing and good designs of airframe geometry can effectively improve the flow characteristic and reduce the drag induced by propeller installation effect.

中文翻译：

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飞翼无人机推进器-螺旋桨安装效果调查与改进

本文通过实验和数值协同研究来研究螺旋桨安装对飞机气动性能的影响，并分析了两种减轻螺旋桨安装效应的方法。正在研究的配置基于真正的飞翼无人机，在其相关机身的后部安装了一个两叶推进器螺旋桨。雷诺平均 Navier Stokes 模拟加上基于结构化有限体积单元顶点的求解器应用于螺旋桨未安装和安装的配置，并且数值结果与实验数据非常吻合。通过螺旋桨未安装和螺旋桨安装情况获得的对比结果表明，由于螺旋桨和机身之间的气动相互作用，推进器-螺旋桨的安装导致最大升阻比下降。对数值结果的详细分析表明，由于安装推进器-螺旋桨而在机身后部产生的低压区将导致基础阻力增加，从而导致最大升阻比下降。通过数值模拟验证了中心轴延伸和修改机身几何形状以减轻螺旋桨安装效应的可行性，