Title

Breakup and coalescence characteristics of a hollow cone swirling spray

Authors

Authors

A. Saha; J. D. Lee; S. Basu;R. Kumar

Comments

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Abbreviated Journal Title

Phys. Fluids

Keywords

LIQUID SHEET; ATOMIZATION; JET; EMULSIONS; DISINTEGRATION; INSTABILITY; COLLISION; BEHAVIOR; NOZZLES; STREAMS; Mechanics; Physics, Fluids & Plasmas

Abstract

This paper deals with an experimental study of the breakup characteristics of water emanating from hollow cone hydraulic injector nozzles induced by pressure-swirling. The experiments were conducted using two nozzles with different orifice diameters 0.3 mm and 0.5 mm and injection pressures (0.3-4 MPa) which correspond to Rep = 7000-26 000. Two types of laser diagnostic techniques were utilized: shadowgraph and phase Doppler particle anemometry for a complete study of the atomization process. Measurements that were made in the spray in both axial and radial directions indicate that both velocity and average droplet diameter profiles are highly dependent on the nozzle characteristics, Weber number and Reynolds number. The spatial variation of diameter and velocity arises principally due to primary breakup of liquid films and subsequent secondary breakup of large droplets due to aerodynamic shear. Downstream of the nozzle, coalescence of droplets due to collision was also found to be significant. Different types of liquid film breakup were considered and found to match well with the theory. Secondary breakup due to shear was also studied theoretically and compared to the experimental data. Coalescence probability at different axial and radial locations was computed to explain the experimental results. The spray is subdivided into three zones: near the nozzle, a zone consisting of film and ligament regime, where primary breakup and some secondary breakup take place; a second zone where the secondary breakup process continues, but weakens, and the centrifugal dispersion becomes dominant; and a third zone away from the spray where coalescence is dominant. Each regime has been analyzed in detail, characterized by timescale and Weber number and validated using experimental data. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773065]

Journal Title

Physics of Fluids

Volume

24

Issue/Number

12

Publication Date

1-1-2012

Document Type

Article

Language

English

First Page

21

WOS Identifier

WOS:000312833500025

ISSN

1070-6631

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