The commercially available unmanned aerial vehicles are not good enough for search and rescue flight at high altitudes. This is because as the altitude increases, the density of air decreases which affects the thrust generation of the UAV. The objective of this research work is to design thrust optimized blade for an altitude range of 3,000–5,000 m with a density of air 0.7364 kg/m³, respectively, and perform thrust analysis. The property of aluminum alloy 1,060 being lightweight is chosen for designing and testing of blade. The blade element theory-based design and analysis code was developed, and user-friendly aerodynamic inputs were used to obtain the desired outputs. The geometry designed for an altitude range of 3,000-5,000 m faced the total stress of 6.0 MPa which was at 70% of the blade span. This stress is within the limit of yield strength of the aluminum alloy, 28 MPa. The modal analysis shows the first natural frequency occurs at around 12,000 RPM which is safe for operating the blade at 0-5,000 RPM. Experimental analysis of the blade gave a thrust of 0.92 N at 2,697 RPM at 1,400 m. The analytical solution for thrust with the same conditions was 1.7 N with 85.6% efficiency. The validation of experimental results has been done by the CFD analysis. The CFD analysis was performed in ANSYS CFX which gave a thrust value of 2.27 N for the same boundary conditions. Thus, the blade designed for high altitude SAR UAV is structurally safe to operate in 0-5,000 RPM range, and its use in search missions could save many lives in the Himalayas.

中文翻译：

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高空搜救无人机螺旋桨的设计与分析

市售的无人机不足以在高空进行搜索和救援飞行。这是因为随着海拔的升高，空气密度降低，这会影响无人机的推力产生。这项研究工作的目的是针对海拔高度为3,000–5,000 m且空气密度为0.7364 kg / m ^3的推力优化叶片进行设计。分别进行推力分析。选择轻质铝合金1,060的性能用于叶片的设计和测试。开发了基于叶片元素理论的设计和分析代码，并使用了用户友好的空气动力学输入来获得所需的输出。设计用于3,000-5,000 m高度范围的几何形状面临着6.0 MPa的总应力，这是叶片跨度的70％。该应力在铝合金的屈服强度极限（28 MPa）内。模态分析显示，第一个自然频率出现在12,000 RPM左右，这对于在0-5,000 RPM下操作刀片是安全的。叶片的实验分析在1,400 m的转速下以2,697 RPM的推力为0.92N。在相同条件下的推力解析解为1.7 N，效率为85.6％。实验结果的验证已通过CFD分析完成。CFD分析在ANSYS CFX中进行，对于相同的边界条件，其推力值为2.27N。因此，专为高空SAR无人机设计的叶片在结构上可以安全地在0-5,000 RPM范围内操作，并且在搜索任务中使用可以挽救喜马拉雅山的许多生命。