Numerical analysis and validation of spray distributions disturbed by quad-rotor drone wake at different flight speeds

The computational fluid dynamics method based on the lattice Boltzmann method (LBM), was used to simulate the downwash flow field of a quad-rotor drone. The downwash flow fields of a quad-rotor drone at flight speeds of 1–7 m/s and flight altitudes of 1–2 m were simulated. The horseshoe-shaped vortices were successfully captured at a speed exceeding 5 m/s. In order to capture the deposition and drift distribution of droplets with different sizes in the downwash flow field of a quad-rotor drone more accurately, the Lagrangian discrete phase particle tracking method was used to simulate the trajectories of droplets with different particle sizes. By changing the flight speed, flight altitude, vertical height of the boom from the rotor, and lateral distance between the nozzles, the effects of these conditions on the droplet deposition and drift behind the fuselage were studied. The accuracy of the numerical simulation was verified by a wind tunnel test. The results of the numerical simulation were in good agreement with the data from the wind tunnel test. It is shown that the computational fluid dynamics model developed in the paper can be successfully applied to the simulations of droplet drift and deposition of a quad-rotor plant protection drone.