1995 Volume 81 Issue 2 Pages 135-140
As for the characteristics of the gas wiping jet in the hot-dip coating process, the flow coefficient, the velocity profile and the impinging wall pressure distribution of a plane jet are investigated using two types of model nozzle.
The friction loss of the wiping nozzle is 1% or less when the ratio of lip length to slit gap is not more than 5. The inner shape of the wiping nozzle has no effect on the characteristics of the wiping jet. The impinging wall pressure at the plate edge is low and the wall pressure distribution is gently as compared with those at the plate center. It is considered that this is the probable cause of edge over coatings. The velocity distribution of the impinging wall jet agrees with Verhoff equation for the wall jet injected parallel to a wall. The velocity scale of the impinging wall jet is affected by the nozzle slit gap and the wiping angle, but the length scale is independent of those values.