The interaction between a propeller and its self-induced vortices originating on the ground is investigated in a scaled experiment. The velocity distribution in the flow field in two different planes containing the self-induced vortices is measured by particle image velocimetry (PIV). These planes are a wall–parallel plane in close proximity to the ground and a wall–normal plane just upstream of the propeller. Based on the visualization of the flow field in these two planes, the occurrence of ground vortices and its domain boundary are analysed. The elevation of the propeller from the ground and the thrust of the propeller are two parameters that determine the occurrence of ground vortices. The main features of the propeller inflow in the presence of the ground vortices are highlighted. Moreover, the analysis of the non-uniform inflow in the azimuthal direction shows that with increasing the propeller thrust coefficient and decreasing the elevation of the propeller above the ground, the variation of the inflow angle of the blade increases.Graphical Abstract

中文翻译：

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粒子图像测速分析螺旋桨引起的地面涡


在规模实验中研究了螺旋桨与其源自地面的自感涡流之间的相互作用。通过粒子图像测速（PIV）测量包含自感涡的两个不同平面中流场的速度分布。这些平面是靠近地面的壁平行平面和螺旋桨上游的壁法线平面。基于这两个平面流场的可视化，分析了地涡的发生及其域边界。螺旋桨距地面的高度和螺旋桨的推力是决定地面涡发生的两个参数。突出显示了存在地面涡时螺旋桨流入的主要特征。此外，对方位角方向非均匀流入的分析表明，随着螺旋桨推力系数的增大和螺旋桨离地高度的减小，桨叶流入角的变化量增大。