Abstract
An experimental study of inert particle dispersion in an isothermal concentric air jet near field was conducted for cases of standard non-staggered and alternative staggered jet nozzles, each taken from a polymer powder flame deposition gun. The experimental work consisted of analysis of high speed digital images of the inert two phase isothermal jet flow, illuminated by a laser light sheet along and across the jet axis. The analysis of particle spread in the jet, represented by families of particle density distributions, clearly showed that the staggered nozzles resulted in a better-focused flow, with narrower distributions in the near field, and in the elimination of the recirculation zone that disrupted the particle flow in a non-staggered nozzle arrangement. In all cases, histograms of the cross-sectional particle area density were found to be approximately Gaussian. It was also found that there was a wide variation in the size and shape of the ground polymer particles used and these two characteristics caused a wide variation in the radial and axial velocities of the particles. Despite the differences between single-phase numerical simulations and experimental results, reported in Payne et al. [1], the introduction of particles into a numerical model produced satisfactory agreement with the particle velocities found experimentally.
Highlights
The industrial process of polymer flame deposition consists of injecting a polymer powder into a flame created by burning air and a gaseous fuel
The current paper reports on studies of isothermal coaxial air jets bearing inert polymer particles created by one of two gun heads with the propane switched off, a gun head used earlier in the same flame deposition process, referred to here as Gun Head 1, and the gun head described by Payne et al [1], referred to here as Gun Head 2, shown in Figure 1a,b respectively
Payne et al [1] show Gun Head 2 has been effective in eliminating the recirculation zone at the exit of the powder air jet, at least over the annular air jet to central air jet velocity ratios used in this work
Summary
The industrial process of polymer flame deposition consists of injecting a polymer powder into a flame created by burning air and a gaseous fuel. The quality and control of the whole deposition process depends critically upon the particle trajectories, and the uniformity and size of the particle jet stream all the way from the spray gun face to the target surface. In this process, the faster annular jet surrounding the particle bearing central jet serves as the main source of momentum for the particles
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
