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Frontiers of Agricultural Science and Engineering

Front. Agr. Sci. Eng.    2018, Vol. 5 Issue (2) : 159-167
The computational fluid dynamic modeling of downwash flow field for a six-rotor UAV
Yongjun ZHENG1(), Shenghui YANG1,2, Xingxing LIU1, Jie WANG1, Tomas NORTON2, Jian CHEN1, Yu TAN1()
1. College of Engineering, China Agricultural University, Beijing 100083, China
2. Department of Engineering, Harper Adams University, Newport TF10 8NB, UK
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The downwash flow field of the multi-rotor unmanned aerial vehicle (UAV), formed by propellers during operation, has a significant influence on the deposition, drift and distribution of droplets as well as the spray width of the UAV for plant protection. To study the general characteristics of the distribution of the downwash airflow and simulate the static wind field of multi-rotor UAVs in hovering state, a 3D full-size physical model of JF01-10 six-rotor plant protection UAV was constructed using SolidWorks. The entire flow field surrounding the UAV and the rotation flow fields around the six rotors were established in UG software. The physical model and flow fields were meshed using unstructured tetrahedral elements in ANSYS software. Finally, the downwash flow field of UAV was simulated. With an increased hovering height, the ground effect was reduced and the minimum current velocity increased initially and then decreased. In addition, the spatial proportion of the turbulence occupied decreased. Furthermore, the appropriate operational hovering height for the JF01-10 is considered to be 3 m. These results can be applied to six-rotor plant protection UAVs employed in pesticide spraying and spray width detection.

Keywords CFD simulation      downwash flow field      numerical analysis      plant protection      six-rotor UAV     
Corresponding Authors: Yongjun ZHENG,Yu TAN   
Just Accepted Date: 19 March 2018   Online First Date: 23 April 2018    Issue Date: 28 May 2018
 Cite this article:   
Yongjun ZHENG,Shenghui YANG,Xingxing LIU, et al. The computational fluid dynamic modeling of downwash flow field for a six-rotor UAV[J]. Front. Agr. Sci. Eng. , 2018, 5(2): 159-167.
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Yongjun ZHENG
Shenghui YANG
Xingxing LIU
Fig.1  JF01-10 plant protection UAV (a) and parts consisting of JF01-10. [1] flight control box; [2] propeller; [3] core circuits; [4] electric motor; [5] arm; [6] battery cabin; [7] pressure nozzle; [8] pesticide tank; [9] landing gear; [10] pump.
Parameter Value Remark
Flight height 2, 3 and 5 m Autonomous set
Main rotor diameter 558 mm (22”) Carbon fiber
Size 1780 × 660 mm Width × height
Weight 15 kg
Maximum load 10 l Maximum capacity
Effective remote control distance 1 km Effective signal of remote controller
Tab.1  Main parameters of JF01-10
Fig.2  Wheelbase and propellers
Part Size (mm) Remarks
Central plate 300 × 300 × 3 Length × width × thickness, chamfering R100
UAV long arm 500 × ø30
UAV short arm 472.5 × ø30
Spray rod 1000 × ø12 10° with undercarriage
Undercarriage ø25 Length was calculated from other values
Tab.2  Dimensions of UAV main parts
Fig.3  Full-size physical model of UAV arm (a) and the body frame (b)
Fig.4  3D model of the propeller
Fig.5  Full-size physical model of the UAV JF01-10
Fig.6  Partitioning of fluid field. (a) Total field portioning; (b) rotation fluid domain; (c) downwash field.
Fig.7  Elements of the rotating (a), upwind (b) and downwash flow (c) fluid domains
Fig.8  Computational results of UAV downwash flow fields with different hovering heights of 2 m (a), 3m (b), 5 m (c), and the relative boundless height (d)
Fig.9  Streamline vectors for different hovering heights of 2 m (a), 3 m (b), 5 m (c), and the relative boundless height (d)
Fig.10  Pressure nephogram at 2 m (a), 3 m (b), and 5 m (c) hovering height
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