Numerical study on mixed thermal-elastohydrodynamic lubrication of grease lubricating lubricated spiral bevel gear for heavy-duty unmanned aerial vehicle

Aiming to solve the problem of the gear lubrication of unmanned aerial vehicles (UVAs), a grease mixed Thermal-elastohydrodynamic lubrication (TEHL) model is established, and the lubrication state of the gearbox of oil-powered heavyduty UAVs is numerically analyzed. In this study, grease is regarded as a non-Newtonian fluid whose properties change nonlinearly with respect to pressure, temperature, and other conditions. The complex meshing state of a spiral bevel gear tooth surface is analyzed using the loaded tooth contact analysis (LTCA) method, and three points on the tooth surface are selected as samples to describe the lubrication state of the entire tooth surface. The thickness of grease film and the temperature rise of the tooth surface are studied in detail, considering the natural roughness of the tooth surface and influence of different greases. The results show that the established model agrees with results from the literature. The dangerous point of tooth surface lubrication is at the meshing midpoint. Under cruise conditions, the lubricating grease viscosity significantly influences the temperature rise of the tooth surface.

针对无人机（UAV）的齿轮润滑难题，本研究建立了润滑脂混合热弹性流体动力润滑（TEHL）模型，并对燃油动力重型无人机的变速箱润滑状态开展数值分析。本研究将润滑脂视为特性随压力、温度等工况呈非线性变化的非牛顿流体；采用加载轮齿接触分析（LTCA）方法解析螺旋锥齿轮齿面的复杂啮合状态，并选取齿面上三个采样点以表征整个齿面的润滑状态。本研究在考虑齿面固有粗糙度与不同润滑脂影响的前提下，详细探究了润滑脂膜厚度与齿面温升。研究结果表明，所建立的模型与文献报道的结果吻合一致；齿面润滑危险点位于啮合中点；在巡航工况下，润滑脂黏度对齿面温升具有显著影响。