Open AccessStructure of the Continuous Liquid Jet Core during Coaxial Air-Blast Atomisation
Author(s) -
Georgios Charalampous,
Y. Hardalupas,
A. M. K. P. Taylor
Publication year - 2009
Publication title -
international journal of spray and combustion dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 16
eISSN - 1756-8285
pISSN - 1756-8277
DOI - 10.1260/175682709789685840
Subject(s) - nozzle , breakup , jet (fluid) , coaxial , mechanics , break up , optics , physics , materials science , weber number , reynolds number , turbulence , thermodynamics , engineering , electrical engineering
This paper investigates the structure of the continuous liquid jet of a coaxial air-blast atomiser over a range of Weber numbers 60-1040, Reynolds numbers of liquid jet 5400-21700 and air to liquid momentum ratios of the two streams of 1.7–335. A novel optical technique, based on internal illumination of the liquid jet through the jet nozzle by a laser pulse, which excites a fluorescing dye introduced in the atomizing liquid, was used to obtain instantaneous measurements of the breakup length and the three dimensional location of the liquid core of the continuous liquid jet. The latter was achieved by simultaneously imaging the liquid jet from two directions normal to each other. Such measurements are usually prevented by droplets surrounding the liquid jet at the dense spray near the nozzle exit. The measurements showed that the break-up length of the liquid jet scaled well with the air to liquid momentum ratio. The standard deviation of the temporal fluctuations of the break-up length was around 10% of the mean breakup length for each considered flow condition. The instantaneous jet surface does not develop axi-symmetric wave structures but the time-averaged liquid jet is axi-symmetric around the nozzle axis, while the maximum deflection of the liquid jet occurs close to the breaking point