Experimental Study of Near-Field Flow Structure in Hollow Cone Pressure Swirl Sprays

In this work the near field of the sprays resulting from the breakup of conical liquid sheets was investigated through experimental techniques. The dispersed and continuous phase velocities and the size of droplets were measured using a phase Doppler particle analyzer. A data postprocessing, applying the generalized integral method, was used to evaluate droplet volume fluxes and total liquid flow rates. The parameters of radial mean spread and spatial dispersion of the sprays were calculated and the overall droplet size distributions across the sprays were obtained. Two sheet disintegration regimes, perforations and surface wave instabilities, were analyzed. Measurements showed a significant increase in the atomization quality as well as in the liquid radial dispersion parameter for the wavy sheet disintegration. In addition, the effects of the collision phenomena on the droplet size distributions were shown. High collision rates were predicted in the spray densest zones and some collision outcomes, as the droplet coalescence or the separation with satellite droplet formation, were detected.