Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Sofija Minov (1, 2, 3) , Frédéric Cointault (2) , Jürgen Vangeyte (1) , Jan Pieters (4) , David Nuyttens (1)

1 Technology and Food Science Unit, Agricultural Engineering
2 Agroécologie [Dijon]
3 Department of Biosystems Engineering, Bioscience Engineering Faculty
4 Faculty of Bioscience Engineering, Department of Biosystems Engineering

Accurate spray characterization helps to better understand the pesticide spray application process. The goal of this research was to present the proof of principle of a droplet size and velocity measuring technique for different types of hydraulic spray nozzles using a high speed backlight image acquisition and analysis system. As only part of the drops of an agricultural spray can be in focus at any given moment, an in‐focus criterion based on the gray level gradient was proposed to decide whether a given droplet is in focus or not. In a first experiment, differentlysized droplets were generated with a piezoelectric generator and studied to establish the relationship between size and in‐focus characteristics. In a second experiment, it was demonstrated that droplet sizes and velocities from a real sprayer could be measured reliably in a non‐intrusive way using the newly developed image acquisition set‐up and image processing. Measured droplet sizes ranged from 24 μm to 543 μm, depending on the nozzle type and size. Droplet velocities ranged from around 0.5 m/s to 12 m/s. The droplet size and velocity results were compared and related well with the results obtained with a Phase Doppler Particle Analyzer (PDPA).

Mots clés: high speed image analysis; spray characterization; piezoelectric droplet generator; in-focus criterion

Domaines: Sciences du Vivant [q-bio]; Traitement du signal et de l'image [eess.SP]

Sofija Minov, Frédéric Cointault, Jürgen Vangeyte, Jan Pieters, David Nuyttens. Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion. Sensors, 2016, 16 (2), art 218 (000019p.). ⟨10.3390/s16020218⟩. ⟨hal-01772998⟩