ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
When thin films of liquid are produced by roll coaters it is commonly observed that the liquid film is not uniform but shows either regular or irregular patterns resulting from hydrodynamic origins. The appearance of the liquid film has been considered to be governed by the flow geometry and dynamics in a nip region between two adjacent solid planes.Experimental work was done to observe the flow geometries in the nip region and patterns of liquid film by using a roll-stationary, transparent flat plate system. Two fundamental mechanisms for rib disappearance in practical high-speed coatings were recognized. It was also found that the constant rib interval for infinite capillary number depends not only upon the minimum gap size but also upon the physical properties of the liquid. Experimental data are presented in dimensionless form for meniscus position, rib interval, constant rib interval, and for the critical or transient conditions of rib formation, rib disappearance, unstead ribbing, and centrifugal splash.Comparison of present results for the speed ratio U2/U1 = 0 with previous results for U2/U1 = 1 shows the significance of the speed ratio to the meniscus position and the rib interval.
Additional Material:
15 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690340313
Permalink
