The influence of rotor downwash on spray distribution under a quadrotor unmanned aerial system
The influence of rotor downwash on spray distribution under a quadrotor unmanned aerial system
复制标题
DOI：
10.1016/j.compag.2022.106807
复制
发表时间：
2022-05
期刊：
影响因子：
--
通讯作者：
M. Coombes;Sam Newton;James Knowles;A. Garmory
中科院分区：
文献类型：
--
作者：
M. Coombes;Sam Newton;James Knowles;A. Garmory
本文研究了作物喷洒时四旋翼无人机系统产生的旋翼下洗流对喷雾的影响。使用流场的 RANS 建模和喷雾的拉格朗日粒子跟踪，对几种单转子和多转子案例进行了计算流体动力学模拟，其中喷雾注入转子中心下方。使用叶片元件执行器盘模型对转子进行建模。该计算方法的准确性通过与室内环境中单个转子的推力和沉积喷雾模式的实验良好吻合得到证明。实验和计算结果都表明，单个转子下喷雾分布的峰值随着转子推力的增加而增加，而增加转子距地面的高度会导致该峰值减小。然后使用经过验证的计算流体动力学方法来模拟单旋翼和多旋翼情况下的飞行条件。这些表明存在临界飞行速度，高于该速度时，撞击地面的喷雾不再包含明显的峰值。这种行为被认为是由于流管与地面分离并且不再将喷雾直接输送到地平面。超过这个临界速度，可以看到喷雾悬浮在无人机系统后面的空气中。这种行为使得现实模拟变得更加困难，因为需要环境湍流条件的详细信息来模拟随后的喷雾传输。从实际角度来看，由于显着喷雾漂移的可能性增加，依赖湍流来输送喷雾是不期望的。
This paper investigates how sprays are influenced by rotor downwash produced by a quadrotor Unmanned Aerial System when crop spraying. Computational Fluid Dynamics simulations, using RANS modelling for the flow field and Lagrangian particle tracking for the spray, are conducted for several single-rotor and multi-rotor cases with the spray injected underneath the centre of the rotor. The rotor is modelled using a Blade Element actuator disc model. The accuracy of the computational approach is demonstrated by good agreement with experiment for both thrust and deposited spray pattern for a single rotor in an indoor environment. Both the experimental and computational results show that the peak in the spray distribution under a single rotor increases as rotor thrust increases, whilst increasing the rotor height above the ground causes this peak to decrease. The validated Computational Fluid Dynamics method is then used to simulate flight conditions for single-rotor and multi-rotor cases. These show the existence of a critical flight speed, above which the spray impinging on the ground no longer contains a notable peak. This behaviour is seen to be due to the streamtube detaching from the ground and no longer carrying the spray directly to the ground plane. Above this critical speed the spray is seen to become suspended in the air behind the Unmanned Aerial System. This behaviour makes realistic simulation more difficult, as details of the ambient turbulence conditions would be needed to model the subsequent spray transport. The reliance on turbulence to transport the spray is undesirable from a practical point of view due to the increased likelihood of significant spray drift.