COLD MODEL EXPERIMENT ON FLUID-FLOW PHENO MENA IN HOT-DIP PLATING BATH

Flow phenomena in a hot dip plating bath were investigated by using co ld models with reduced scale of 1/5 and 1/10. The flow pattern, mean v elocity components, root-mean-square Value of turbulence components an d Reynolds shear stress in the bath were measured using a hot-wire ane mometer and a two-channel laser Doppler velocimeter (LDV). The flow pa ttern in the bath was three dimensional. Main flow induced by belt mot ion on the entry side moved into the exit side and subsequently return ed along the side walls and the bottom wall to the entry side. A part oi the flow returning along the side walls to the entry side entered f rom the edges of the belt into the region enclosed with the belt. The flow pattern in the region enclosed with the belt was also three dimen sional. The flow pattern in the whole bath was in good agreement with that suggested by mean velocity vectors measured with the LDV. Mean ve locity components and the root-mean-square value of turbulence compone nts were altogether low in the almost all part of the entry side regio n except near the belt. A great amount of dress accompanied with flow in a practical hot dip plating bath seems to exist in this region. As the Reynolds shear stress was very high in the vicinity of the strip e xtending from the sink roll to the exit side, the dress would be vigor ously disturbed and dispersed there.