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Modeling the Formation of Urea-Water Sprays from an Air-Assisted Nozzle

Frühhaber, Jens; Lieber, Christian; Mattes, Dominik; Lauer, Thomas; Koch, Rainer; Bauer, Hans-Jörg

Abstract (englisch):
Ammonia preparation from urea-water solutions is a key feature to ensure an effective reduction of nitrogen oxides in selective catalytic reduction (SCR) systems. Thereby, air-assisted nozzles provide fine sprays, which enhance ammonia homogenization. In the present study, a methodology was developed to model the spray formation by means of computational fluid dynamics (CFD) for this type of atomizer. Experimental validation data was generated in an optically accessible hot gas test bench using a shadowgraphy setup providing droplet velocities and size distributions at designated positions inside the duct. An adaption of the turbulence model was performed in order to correct the dispersion of the turbulent gas jet. The spray modeling in the near nozzle region is based on an experimentally determined droplet spectrum in combination with the WAVE breakup model. This methodology was applied due to the fact that the emerging two-phase flow will immediately disintegrate into a fine spray downstream the nozzle exit, which is also known from cavitating diesel nozzles. The suitability of this approach was validated against the radial velocity and droplet size distributions at the first measurement position downstream the nozzle. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000122871
Veröffentlicht am 24.08.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Thermische Strömungsmaschinen (ITS)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 2076-3417
KITopen-ID: 1000122871
Erschienen in Applied Sciences
Band 10
Heft 16
Seiten Article no: 5723
Vorab online veröffentlicht am 18.08.2020
Schlagwörter CFD; droplet kinematics; gas jet; injection processes; selective catalytic reduction; shadowgraphy; spray characteristics; turbulent dispersion
Nachgewiesen in Scopus
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