Liquid Film Formation by an Impinging Jet in a High-Velocity Air Stream

Abstract

The impingement of a liquid jet on a solid surface, and the development of a shear-driven liquid film is characterized in a planar experiment. Weber number and momentum-flux ratios were chosen to be representative of gas turbine fuel injector operations. High-speed digital imaging was used to visualize the formation of the liquid film from impinging droplets and the development of a continuous, wavy film. Film thickness measurements indicated growth of the film along the length of the impinging surface (streamwise direction), and reduction in the film thickness in the crossstream direction. In general, film thicknesses increased with increasing momentum flux ratio, as more liquid drops reached the filmer surface. Three different mechanisms of atomization from the liquid film were identified.namely droplet splashing, film surface atomization via aerodynamic instability and film breakup at channel exit.