CHARACTERISTICS OF THE SPRAY PRODUCED BY THE ATOMIZATION OF AN ANNULAR LIQUID SHEET ASSISTED BY AN INNER GAS JET

This article deals with the properties of the "Christmas tree" disintegration mode of an annular liquid sheet assisted by an inner gas jet. The geometric characteristics of the spray are investigated first, observing that the break-up length decreases when the gas to liquid momentum ratio and the gas swirl rise; the initial spray angle declines with growing ambient pressure and the half width at half maximum of the axial liquid flux rises with increasing swirl intensity, gas to liquid momentum ratio and decreasing ambient pressure. Subsequent analysis of the dispersed phase was conducted using a phase Doppler analyzer, observing that in the midfield, the Sauter Mean Diameter increases from the flow axis to the periphery of the spray. It decreases as the swirl intensity and the gas to liquid momentum ratio rise and declines slightly with a decreasing ambient pressure. The mean radial and axial velocities of droplets and their fluctuations are also presented. As the spray develops, it displays a number of properties very similar to a single jet, such as the self-similarity length however other aspects are very different. For example, the axial velocity fluctuation is maximized on the flow centerline, due to the mechanism of the spray formation.