Abstract: Combining numerical simulation with computational fluid dynamics software and physical experiment， the effects of spray disc rotation speed， spacing between discs， distance between spray disc and steel strip and the number of spray discs on the particle size distribution and atomization result of spraying for steel passivation were studied. The results show that， the faster the disc speed is， the faster is the atomized droplet speed， the smaller is the size of the droplets， and the better is the atomization effect. The disc speed is selected as 6000r/min. When the distance between spray disc and steel strip is 100mm， the droplets size distribution on strip is the best. When the spacing between spraying discs changes， the droplets interference area and collision between droplets will change accordingly， and 80mm is the best spacing. The chromium-free passivation product prepared by using the selected parameters is better than the original passivation product， showing the rationality of the parameter selection.

Key words: chromium-free passivation; spray disc atomization; interference phenomenon; droplet breaking; droplet distribution