DEVELOPMENT OF TOTAL NUMERICAL ANALYSIS METHOD CONSISTING OF GAS FLOW AND LIQUID FILM FLOW TO PREDICT THE COATING WEIGHT

摘要

In the gas wiping process for continuous hot-dip coating, the coating thickness profile of the liquid film flow on a strip steadily moving upward from a coating liquid bath can be accurately estimated by totally solving both the gas flow and the liquid film flow. The analytical results of the jet velocity and the turbulent energy profiles near the strip using the SSTk-ω turbulent model agree well with the experimental results measured by the LDV system. The coating thickness is theoretically estimated by solving the equation of motion using the impinging pressure and the shear stress solved by the gas wiping jet simulation as the boundary condition. The analytical results are also compared with the data obtained on a commercial hot-dip galvanizing line. As a result, it is confirmed that the coating weight can be estimated by the line speed, the nozzle pressure, the nozzle-to-strip distance, and the nozzle slit gap within 6% accuracy.