MATHEMATICAL MODEL OF LIQUID PHASE MOTION IN A ROTARY CUP ATOMIZER FOR SEED TREATMENT IN A FLUIDIZED BED

Abstract

The paper investigates the motion of the liquid phase in a rotary cup atomizer used for pre-sowing treatment of seed material in a fluidized bed. A key requirement of the process is the formation of fine droplets (≤ 50 μm), which prevents particle agglomeration and ensures uniform coating formation on the seed surface. A critical analysis of existing atomization models is carried out, revealing their limitations in describing heterogeneous suspensions, non- Newtonian behavior, and conical geometries. To address these issues, an improved mathematical model of liquid flow along the conical surface of a rotary cup atomizer is proposed. The model is based on the balance between centrifugal and viscous forces and takes into account pseudoplastic rheological properties of the liquid. A dimensionless Hg criterion is introduced to characterize the hydrodynamic regime of the liquid film and to determine the conditions for stable single-layer flow. This regime is essential for controlled atomization and achieving the required droplet size. Relationships between film thickness, rotational speed, liquid flow rate, and droplet diameter are established. In addition, a thermal model is developed to ensure that the seed surface temperature does not exceed 40°C, which is necessary for maintaining seed viability. Numerical analysis confirms the adequacy of the proposed model and demonstrates the possibility of achieving optimal spraying conditions for concentrated suspensions