New quantitative method to measure spray structure (spatial distribution of specific surface area) by using planar laser imaging

Abstract

A new method to measure the distribution of specific surface area (total projection area of particles in a unit volume) is derived theoretically. The distribution of specific surface area is reconstructed from the intensity of light scattered in the direction of 90 degrees to the travelling direction of the light sheet irradiated on the spray. It is a feature of this method that the specific surface area distribution can be measured quantitatively by taking into account the extinction of the light through the spray. In order to confirm the validity of this method, the specific surface area of the sprays injected from two air blast nozzles arranged in parallel was measured by this method. In addition, the results were compared with the results measured by a light extinction method combined with CT process. The distribution of the specific surface area measured by this method agreed with that by the light extinction method. Furthermore, a method to measure the specific surface area instantaneously in an arbitrary two-dimensional cross section is proposed. In this method, the specific surface area is calculated from the ratio of the light intensities scattered in the directions of 90 and -90 degrees to the travelling direction of two parallel laser sheets. However the verification of this method with actual spray is a future task.