Study of Near-Cup Droplet Breakup of an Automotive Electrostatic Rotary Bell (ESRB) Atomizer Using High-Speed Shadowgraph Imaging

Abstract

Electrostatic Rotary bell (ESRB) atomizers are used as the dominant means of paint application by the automotive industry. They utilize the high rotational speed of a cup to induce primary atomization of a liquid along with shaping air to provide secondary atomization and transport. In order to better understand the fluid breakup mechanisms involved in this process, high-speed shadowgraph imaging was used to visualize the edge of a serrated rotary bell at speeds varying between 5000 and 12,000 RPM and with a water flow rate of 250 ccm. A multi-step image processing algorithm was developed to differentiate between ligaments and droplets during the primary atomization process. The results from this experiment showed that higher bell speeds resulted in a 26.8% reduction in ligament and 22.3% reduction in droplet Sauter Mean Diameters (SMD). Additionally, the ligament (ranging from 40 to 400 µm) diameters formed bimodal distributions, while the droplet (ranging from 40 to 300 µm) diameters formed a normal distribution. Velocities were also measured using particle tracking velocimetry, in which size-dependent velocities could then be computed. Droplet velocities were affected more by rotational speed than droplet SMD, while ligaments were affected by other factors than the rotational speed and ligament SMD.

Fabrication and Evaluation of a Novel Non-Invasive Stretchable and Wearable Respiratory Rate Sensor Based on Silver Nanoparticles Using Inkjet Printing Technology

“…They reported an error of −0.32 ± 0.68 Hz (Mean difference ± Standard Deviation of difference) compared with the reference sensor. However, these sensors are burdensome with electromagnetic radiation and high energy consumption, and inconvenient for daily use, especially under low-resource conditions, with the worldwide concern on global warming [12] and increase in energy demand forcing industries to continuously look for enhancements to their processes and energy usage [13,14].…”

Optimization of Geometry Parameters of Inkjet-Printed Silver Nanoparticle Traces on PDMS Substrates Using Response Surface Methodology

“…With the increase in energy need worldwide [32], industries are continuously researching enhancements to their energy utilization and processes execution [33,34]. Other studies have investigated various operating parameters for optimal operation [35], either for high scale power demand [36] or a lower scale [37]; however, inkjet optimization studies presented in the literature [38,39,40,41] were mainly concerned with optimal process parameters, such as sintering parameters and nozzle settings.…”

Spatial Positioning and Operating Parameters of a Rotary Bell Sprayer: 3D Mapping of Droplet Size Distributions

“…The experimental techniques in these investigations, including qualitative hydrodynamics, diffraction spectrometry, and short spark photography, were used to delineate the spray droplet size distributions and the fluid atomization mode at the edge of the bell. Optical diagnostic techniques, such as shadowgraphy high-speed imaging [23], have also been used to measure droplet diameters and distributions from different atomizers.…”