Experiments describe physics of how filament extension atomizers spray viscous and elastic fluids

Most conventional spray systems are hampered by poor performance with viscous and elastic fluids. Diluting viscous substrates for use in conventional nozzles, however, significantly increases energy consumption. Filament extension atomizers (FEAs) are a new class of spray nozzles using rollers to atomize fluids that have shown promise for atomizing high-viscosity and non-Newtonian fluids — fluids whose thickness depends on external factors, like applied force. To date, however, there has been relatively little work that explains their superior performance.

Neelakantan et al. have investigated the effects of roller geometry, surface velocity, roller material, and fluid rheology on the atomization performance of FEA systems. Using extensional and shear rheology with high-speed imaging and particle image velocimetry, the group found the filament breakup dynamics are governed by competition between inertial, capillary, and viscoelastic stresses in whey protein suspensions.

“In the near term, this work has the potential to significantly improve the efficiency of spray drying processes,” said author Ravi Neelakantan. “By enabling atomization of higher-viscosity (or solids concentration) feeds, it can significantly lower the energy intensity of large-scale manufacturing in food and chemical industries.”

The group found that high roller rotational velocity leads to narrower spray cones, and smaller rollers at the same velocity had broader spray cones, demonstrating that FEA technology can achieve industrially relevant spray cone angles like those generated by pressure nozzles.

“The ability to atomize viscous and elastic fluids with a narrow distribution opens opportunities in pharmaceutical manufacturing, where spherical and narrowly distributed particles are highly desirable, as well as in areas such as thermoplastic powder production and aerosol delivery of viscous formulations,” Neelakantan said.

They next look to investigate airflow modeling as well as the effects of different fluids, materials, and feed rates.

Source: “Filament extension atomizers: A study of integration potential into spray dryers for high-viscosity and non-Newtonian fluids,” by Ravi Neelakantan, Nicolas J. Alvarez, Thamires A. Lima, Aditya Sangli, Eric Weflen, Benjamin Boggs, Gregory Anderson, and David M. Johnson, Physics of Fluids (2026). The article can be accessed at https://doi.org/10.1063/5.0302696 .