Measurements of Diesel Spray Droplet Size with Ultra-Small Angle X-Ray Scattering


Alan Kastengren , Daniel Duke,Alan Kastengren,Jan Ilavsky


The strong scattering of visible light by spray droplets has severely impeded the ability of optical diagnostics to probe dense sprays. X-rays interact more weakly with spray droplets than visible light, and the dominant interaction of x-rays with droplets is absorption, rather than scattering. As such, x-ray radiography (which relies on absorption) and x-ray phase-contrast imaging (which relies on subtle refractive and diffractive effects at phase boundaries) have provided important insights regarding the breakup of dense sprays. The current study extends these measurements to study the droplet size in the near-nozzle region of diesel sprays using ultra-small angle x-ray scattering (USAXS). Though USAXS has been used to study particle size in many systems, this is the first attempt to use it to study high-speed sprays. The principles underlying the USAXS measurements will be described, and initial measurements of a diesel spray from a single-hole nozzle will be shown over a range of conditions.



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Alan Kastengren


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