Hydrodynamics of Liquid Jet Application in High-Speed Jet Coating

The visualization of the impingement flow has allowed the determination of the stable coating conditions. In the stable coating window, an apparent contact line was obtained from the analysis of the jet free surface profiles. Results showed that the trend for the deflection and the development length of the liquid layer at high web speed is different from that at low speed. The apparent contact line location for web speed ranging from 4.1 to 8.3 ms−1 has been suitably explained with the boundary layer model while the force balance model better applies at high web speed (U > 12.5 ms−1). The effects of the air pressure generated by the moving web, the jet impinging pressure and the rheological properties of fluids on the location of the apparent contact line have also been assessed.