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The effect of nozzle geometry on the flow characteristics of small water jets

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journal contribution
posted on 21.04.2009, 13:54 by E. Ghassemieh, Hendrik Versteeg, Memis Acar
A wide variety of processes make use of plain orifice nozzles. Fuel injectors for internal combustion engines incorporate these nozzles to generate finely atomized sprays. Processes such as jet cutting, jet cleaning, and hydroentanglement, on the other hand, use similar nozzles, but require coherent jets. The spray or jet characteristics depend on the stability of the flow emerging from the orifice. This problem has been extensively researched for nozzles with diameters above 300 μm. Much less is known about the characteristics of jets produced by nozzles with smaller diameters, where viscous effects and small geometric variations due to manufacturing tolerances are likely to play an increasing role. Results are presented of a wide-ranging investigation of geometry effects on the flow parameters and jet characteristics of nozzles with diameters between 120 and 170 μm. Nozzles with circular cross-section and conical, cone-capillary and capillary axial designs were investigated. For conical and conecapillary nozzles, the effect of cone angle and effects due to interactions between adjacent nozzles in the multi-hole cone-capillary nozzles were studied. For capillary nozzles, the effects of diameter variations and inlet edge roundness for capillary nozzles were considered. Furthermore, the effect of varying the aspect ratio (ratio of major and minor axes) of elliptical nozzles was studied. Flowrate and jet impact force measurements were carried out to determine the discharge coefficient Cd, velocity coefficient Cv, and contraction coefficient Cc of the nozzles for supply pressures between 3 and 12 MPa. Visualizations of the jet flow were carried out in the vicinity of the nozzle exit in order to identify near-nozzle flow regimes and to study jet coherence. The relationship between nozzle geometry, discharge characteristics, and jet coherence is examined.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Citation

GHASSEMIEH, E., VERSTEEG, H.K. and ACAR, M., 2006. The effect of nozzle geometry on the flow characteristics of small water jets. Proceedings of the IMechE Part C: Journal of Mechanical Engineering Science, 220 (12), pp. 1739-1753

Publisher

© Professional Engineering Publishing

Version

VoR (Version of Record)

Publication date

2006

Notes

This is an article from the journal, Proceedings of the IMechE, Part C: Journal of Mechanical Engineering Science [© Professional Engineering Publishing ]. It is also available at: http://journals.pepublishing.com/content/119771/?p=e7e3b39c3e364460aff8ccff9f3d7f35&pi=0

ISSN

0954-4062

Language

en