Spray characteristics and liquid distribution of multi-hole effervescent atomisers for industrial burners
Vlastnosti spreje a rozložení tekutiny u víceotvorových trysek pro průmyslové hořáky
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The present paper provides an experimental study and optimization of multi-hole effervescent atomizers for industrial burners using oil-based fossil, bio- or waste fuels with prospects of emission reduction. Several multi-hole nozzles were designed based on our previous work. We probed the spray quality by Phase-Doppler anemometry. 3-D plots of Sauter mean diameter and mean droplet velocity demonstrate their spatial distribution within the spray. The effect of geometrical and operational factors on the spray is discussed. Droplet size–velocity correlations as well as the size and velocity distributions are presented, and differences are found against other investigations. A spray macrostructure is photographically observed and spray cone angles of the multi-hole nozzles are analysed. An internal two-phase flow is estimated using the Baker’s map for horizontal two-phase flow. Our previous two-phase flow visualizations suggested a liquid–gas gravitational separation when the multi-hole atomizer operated horizontally. This issue is addressed here; the results of spray heterogeneity measurements document that fuel flow rates through individual exit holes differ significantly. This difference spans between 0 and 70% depending on the nozzle design and flow regime. Effervescent sprays are unsteady under some operating conditions; spray unsteadiness was detected at low pressure and low gas-to-liquid-ratios.Tato práce poskytuje experimentální data a optimalizaci víceotvorových trysek pro průmyslové hořáky na fosilní paliva na bázi oleje, bio- nebo odpadních paliva s cílem na snižování emisí.
KeywordsDroplet size, Effervescent atomization, Liquid–gas separation, Multi-hole atomizers, Spray unsteadiness, Two-phase flow
Document typePeer reviewed
SourceApplied Thermal Engineering. 2016, vol. 96, issue 1, p. 286-296.