Liquid Spray Impact onto Flat and RigidWalls:Formation and Spreading of AccumulatedWall Film

This study presents a combined experimental and theoretical investi- gation on the formation and spreading of a liquid film on a flat and rigid wall due to spray impact. A dual-mode phase Doppler instrument is used to characterise the spray while the average film thickness is measured using a high-speed CCD camera. The experimental results are complemented with theoretical expression- s derived under the assumption that the spray is stationary. A new model for the prediction of the average wall film thickness is formulated taking into account the mean Reynolds number of the impacting drops, the flux density of the impacting droplets, and the average drop diameter. The theoretically determined average film thickness exhibits a good agreement with the measured data when the film can be considered thin.