Publication detail
Experimental analysis of spatial evolution of mean droplet diameters in effervescent sprays
BROUKAL, J. HÁJEK, J.
Czech title
Experimentální analýza prostorového vývoje průměrných průměrů kapek v effervescentních sprejích
English title
Experimental analysis of spatial evolution of mean droplet diameters in effervescent sprays
Type
conference paper
Language
en
Original abstract
Effervescent atomization has established itself in the past decade as a promising alternative to conventional spray formation mechanisms. A great effort is currently being put into understanding the involved phenomena and developing numerical models to predict outcomes of processes relying on effervescent atomizers (i.e. spray combustion, coating, drying). This still proves to be a formidable challenge as effervescent atomization is a complex process involving two phase flow. The presented paper focuses on mean droplet sizes and how they vary throughout effervescent sprays at different operating conditions. The experiment was performed using Phase Doppler Anemometry (PDA) and the droplet data were collected in multiple locations varying both axially and radially. At each measurement location the Sauter Mean Diameter (SMD) was computed. The preliminary results show that closer to the spray nozzle the bigger droplets are concentrated in the spray core, while the small droplets are in the peripheral regions. However, this trend is slowly reversing with increasing distance from the spray nozzle. Finally, from a certain distance the initial trend is completely reversed with the small droplets being in the spray core, while larger droplets are found closer to the edge of the spray. Moreover, this phenomenon seems to be independent of operating conditions. Reasons for such behaviour are suggested and discussed. Furthermore, SMD sensitivity to operating conditions is analysed.
Czech abstract
Effervescentní atomizace se etablovala v posledních deseti letech jako slibná alternativa k běžným mechanismům tvorby sprejů. Velké úsilí je v současné době věnováno pochopení zúčastněných jevů a rozvoj numerických modelů pro predikci výsledku procesů závislých na effervescentních rozprašovačích (tj spalování, nanášení, sušení). To je stále velká výzva, jelikož effervescentní atomizace je komplexní proces, který zahrnuje dvě fáze toku. Předkládaná práce se zaměřuje na střední velikostí kapek a na to, jak se tyto liší v effervescentních sprejích při různých provozních podmínkách. Experiment byl proveden za použití Dopplerovy fázové anemometrie (PDA) a data kapek byly shromážděny v různých axiálních i radiálních pozicích. V každém měřicím místě byl vypočítán Sauterův střední průměr kapky (SMD). Předběžné výsledky ukazují, že blíže u trysky jsou větší kapičky soustředěny v jádru spreje, zatímco malé kapičky jsou v okrajových regionech. Nicméně, tento trend se pomalu obrací s rostoucí vzdáleností od rozprašovací trysky. Konečně, v určité vzdálenosti je počáteční trend zcela opačný, tj. malé kapičky jsou v jádru spreje, zatímco větší kapičky jsou zjištěny blíže k okraji spreje. Navíc, tento jev se zdá být nezávislý na provozních podmínkách. Důvody pro takové chování jsou navrženy a projednány. Kromě toho, je analyzována citlivost na provozních podmínkách.
English abstract
Effervescent atomization has established itself in the past decade as a promising alternative to conventional spray formation mechanisms. A great effort is currently being put into understanding the involved phenomena and developing numerical models to predict outcomes of processes relying on effervescent atomizers (i.e. spray combustion, coating, drying). This still proves to be a formidable challenge as effervescent atomization is a complex process involving two phase flow. The presented paper focuses on mean droplet sizes and how they vary throughout effervescent sprays at different operating conditions. The experiment was performed using Phase Doppler Anemometry (PDA) and the droplet data were collected in multiple locations varying both axially and radially. At each measurement location the Sauter Mean Diameter (SMD) was computed. The preliminary results show that closer to the spray nozzle the bigger droplets are concentrated in the spray core, while the small droplets are in the peripheral regions. However, this trend is slowly reversing with increasing distance from the spray nozzle. Finally, from a certain distance the initial trend is completely reversed with the small droplets being in the spray core, while larger droplets are found closer to the edge of the spray. Moreover, this phenomenon seems to be independent of operating conditions. Reasons for such behaviour are suggested and discussed. Furthermore, SMD sensitivity to operating conditions is analysed.
Keywords in English
Effervescent spray, Phase Doppler Anemometry, atomization
RIV year
2014
Released
27.08.2014
Publisher
AIDIC Servizi S.r.l.
Location
Milano
ISBN
978-88-95608-30-3
ISSN
2283-9216
Book
17th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction
Volume
39
Pages from–to
780–786
Pages count
6
BIBTEX
@inproceedings{BUT109946,
author="Jakub {Broukal} and Jiří {Hájek},
title="Experimental analysis of spatial evolution of mean droplet diameters in effervescent sprays",
booktitle="17th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction",
year="2014",
volume="39",
month="August",
pages="780--786",
publisher="AIDIC Servizi S.r.l.",
address="Milano",
isbn="978-88-95608-30-3",
issn="2283-9216"
}