From Manual Spraying to Robotic Ultrasonic Atomization in Poultry Immunization
Intensive poultry farming requires effective epidemic control, with spray immunization being crucial for preventing respiratory diseases like Newcastle Disease. Optimal vaccine particle size ranges from 30 to 200 micrometers (μm). Traditional manual spraying is inefficient, non-uniform, and labor-intensive, while conventional pressure sprays offer poor droplet control.
Ultrasonic microporous atomization provides uniform, fine droplets but has been underexplored for poultry immunization. Previous studies have focused on medical or industrial applications, primarily using experimental or theoretical approaches. They lack multiphysics-coupled simulations of droplet formation and diffusion specific to poultry house conditions. To fill this gap, this paper designed an atomization component for immunization robots. It determines the optimal driving frequency via modal analysis, simulates droplet formation and diffusion using numerical methods, and validates the model experimentally, ensuring precise, efficient spraying.
Simulation and Experimental Framework for Piezoelectric Microporous Atomization
The robotic system comprises a tracked mobile platform, an immunization atomization component, a data monitoring module, and a control system. The core innovation lies in the atomizer, which uses a piezoelectric microporous atomization plate driven at an optimal frequency of 113 kilohertz (kHz), determined through modal and harmonic response analysis using COMSOL simulation. At this frequency, the central displacement amplitude reaches 5.3 μm, ensuring efficient atomization.
A multi-scale numerical simulation framework is established. First, a single-pore droplet generation model using the Volume of Fluid (VOF) method captures the liquid breakup process, with 230,656 mesh elements ensuring mesh independence. Initial droplet velocity and diameter are extracted as boundary conditions. Second, a droplet diffusion model employing the Discrete Phase Model (DPM) and Rosin-Rammler distribution simulates the spatial evolution of the atomization field, using 56,150 meshes.
To validate the simulations, experiments are conducted using the VisiSize P15 droplet size measurement instrument, which employs Particle Digital Image Analysis (PDIA) technology. The atomization plate parameters match the simulation. Multiple characteristic frequencies (28, 57, 113, and 127 kHz) are tested, with 113 kHz expected to produce optimal performance.
For each measurement, 10,000 particles are collected with three repeated experiments to ensure reliability. Droplet size and velocity are measured at various distances from the atomizer under the resonant frequency of 113 kHz. This combined simulation-experiment approach enables accurate prediction of diffusion distance, spray angle, and droplet size distribution, key indicators for effective poultry immunization.
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Simulation and Experimental Validation of Droplet Atomization Performance
The numerical simulations reveal that droplets ejected from a single micropore reach a peak velocity of 2.76 meters per second (m/s) at detachment. Within one driving cycle (113 kHz), a liquid neck forms and breaks into three to five spherical droplets with initial sizes around 14.6 μm. The diffusion simulation shows that the atomization field reaches a dynamic steady state at 180 milliseconds (ms), with an axial diffusion distance of 68.36 centimeters (cm) and a spray angle of 32°. The velocity decays from 1.72 m/s at 10 cm to 0.26 m/s at 50 cm. Notably, within 15–55 cm from the atomizer, over 90% of droplets fall within the optimal immunization size range of 30-200 μm.
Experimental validation using the VisiSize P15 instrument confirmed that 113 kHz produces the best atomization effect, while 28 kHz fails to atomize, and 127 kHz yields a bimodal particle size distribution with poor uniformity. The measured diffusion angle was approximately 30° with a 65 cm distance. Comparing simulations with experiments, absolute relative errors were below 7% for morphology, below 10% for particle size, and below 18% for velocity (absolute error <0.15 m/s). These results demonstrate that the proposed atomization system meets poultry house immunization requirements, though future work should address multi-pore coupling and solution property effects.
Implications for Poultry Immunization Spraying
This study successfully designed a piezoelectric microporous atomization sprayer for poultry house immunization robots. Through modal analysis, 113 kHz was identified as the optimal driving frequency, enabling stable atomization with a diffusion distance of ~65 cm and spray angle of ~30°. Simulation and experimental results showed good agreement, with relative errors below 10% for particle size and below 18% for velocity.
Within 15–55 cm from the atomizer, over 90% of droplets fell within the required 30–200 μm range. These findings validate the reliability of the multiphysics simulation model and provide technical guidance for intelligent, precise immunization spraying in intensive poultry farming.
Journal Reference
Ning, Z., Li, Q., Zhao, Y., Feng, Q., Gao, R., Guo, X., & Kan, Z. (2026). Droplets formation and diffusion simulation and test of microporous atomizer for robotic immunization spraying. Scientific Reports. DOI:10.1038/s41598-026-48149-3, https://www.nature.com/articles/s41598-026-48149-3
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