Effect of wedge air knife on uniformity of zinc coating in continuous hot-dip galvanizing process

The distribution of impinging jet pressure and temperature on the surface of strip steel in continuous hot-dip galvanizing gas-jet wiping process was simulated by computational fluid dynamics method.Simulation results show that the edge over coating defect is more likely to happen due to the pressure decreases in 5mm range of steel strip edge and the heat dissipation in the edge is relatively faster than that in the central region.To prevent edge over coating,wedge lip edge openmouthed size of air knife was increased.The edge pressure decreases can be effectively impeded by using the air knife,and the edge coating thinning rate increases linearly with the linear growth of wedge openmouthed size.As the parallel section width is 1.10mm,the uniformity of zinc coating is improved when the wedge openmouthed size is from 1.18 mm to 1.22mm.