Thickness Measurement of Film Flow Discharged from a Rectangular Nozzle using light absorption

Space separation using a liquid film instead of the firewall can be considered as a method to prevent such accidents and to block heat and toxic substances. However, few research has been conducted from the viewpoint of the formation of a stable liquid film. In this study, we investigated the flow characteristics of the liquid film discharged from a nozzle with a high aspect ratio. The liquid film thickness was measured by measuring light absorption by fluorescence dye dissolved in the liquid, and the film width was measured from the image of the liquid film. As a result, we found that (1) the film thickness in the edge region becomes thicker toward the downstream, (2) the cross-sectional area of the liquid film decreases downward due to the acceleration of the flow, which is greater than the gravitational acceleration, and (3) the presence of side walls suppresses the decrease in the film width due to the Coanda effect.