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ISSN Druckformat: 1044-5110
ISSN Online: 1936-2684
Indexed in
ENTRAINMENT CONTROL FOR LIGAMENT-CONTROLLED EFFERVESCENT ATOMIZER SPRAYS
ABSTRAKT
Ligament-controlled effervescent atomization (LCEA) was developed as a means of reducing effervescent atomizer air-to-liquid ratios by mass (ALR) from 2% to as low as 0.75%. This reduction in ALR offers an obvious advantage in numerous applications (e.g., combustion systems because of reduced parasitic losses or paint/coating sprays because of improved penetration into corners). Reduction of ALR is a necessity for consumer product sprays because of the limited quantity of atomizing air available in a prepressurized package.
This study focused on passive control of entrainment by ligament-controlled effervescent atomizer sprays. Spray control was investigated by considering the entrainment-modifying effects of four exitorifice geometries having a common diameter of 0.38 mm but different indeterminate-origins—four-point crown, two-point crown, inclined, and stepped. Each geometry was tested at two liquid mass flow rates (0.5 and 0.6 g/s), four air-to-liquid ratios (0.75 ≤ ALR ≤ 2.0%), and four axial distances (67 ≤ x/d0 ≤ 417). Data were acquired for a single bulk liquid—water. Both the atomizing gas and the entrainment gas were dried, high-pressure air.
Steady entrainment rate and momentum rate data were used to calculate entrainment numbers, E, for sprays produced using each of the entrainment-modifying geometries. Results of this experimental investigation are summarized as follows: (1) Normalized entrainment rates (me/ml) were found to scale linearly with normalized axial distance (x/d0) and to increase with increasing ALR for all exitorifice geometries. (2) Entrainment numbers were found to increase with increasing ALR for all exitorifice geometries. (3) The four-point and two-point crowns were found to enhance entrainment by the sprays, whereas the inclined and stepped exits were found to suppress it.
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