MSC Seminar. 07/10/2024. Fateh Rabehi (MSC): “Hydrodynamics of Short Liquid Curtains for Coating.”

Saint-Gobain designs, produces, and distributes materials whose surfaces are often treated with liquid coatings to meet specific aesthetic or functional requirements. One of the most widely used techniques to apply these coatings is the liquid curtain method, where the substrate passes through a vertical sheet of liquid. However, the coating thickness achievable is limited by curtain instability and the entrainment of air between the deposited layer and the moving substrate.

Recent studies have shown that the slot-die coating technique offers a reliable solution to overcome these limitations, but it presents challenges on rigid substrates with height variations. These irregularities can lead to uneven deposits and even the risk of collision with the coating head. By pressurizing the liquid in a ”short curtain” mode, it may be possible to minimize these risks while maintaining the reliability of laminar coating. This allows the head to be positioned at a greater distance, a few millimeters or even centimeters, from the substrate surface.
The aim of this project is to establish a predictive description of these short curtain flows by combining experimental approaches, numerical simulations, and theoretical work. The main goal is to understand how these short liquid curtains are deposited onto the substrate surface as a function of the substrate’s velocity.