Spray Structure from Swirl Atomizers. 3rd Report, Dimensionless Expression of Spray Characteristics.

Abstract

Spray characteristics such as the spatial distributions of drop size and drop velocity are expressed by dimensionless formulae. They are dimensionless when expressed as the Sauter mean drop size and mean drop velocity in the sheath respectively. Furthermore, the Sauter mean drop size and mean drop velocity in the sheath can be derived using injection pressure, atomizer's characteristics and axial distance. The spray angle can be derived the Renolds number and Flow factor in the swirl chamber. The maximum deviations of the empirical formulae for the Sauter mean drop size, mean drop velocity and spray angle are less than 12%. On the other hand, the border lines of the spray structure model are decided quantitatively. The boundary between the main flow region and stagnated flow region are divided by the dimensionless number Sg which is defined in this paper. The boundary between the entrained flow region and sheath region are divided by the variation of the correlation coefficient for drop size and drop velocity in the radial direction.