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Investigation of LDPE blown film instability induced by air cooling
Author(s) -
Zhang Z.,
Lafleur P.G.
Publication year - 2008
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.21112
Subject(s) - bubble , materials science , instability , airflow , mechanics , air bubble , heat transfer , aerodynamic heating , composite material , thermodynamics , physics
This paper deals with the bubble instabilities induced by cooling airflow rate at different take‐up‐ratio (TUR) and blow‐up‐ratio (BUR) conditions in the film‐blowing process. Experimental methods to monitor the on‐site bubble instability included an in‐line scanning camera system to record the bubble oscillation and a manometer mounted on the die to measure the internal pressure corresponding to the radius variation. A good correlation between the bubble instability and the pressure inside the bubble has been obtained. Experimental results indicated that varying the cooling airflow rate at different TURs and BURs conditions produced significant differences in the dynamics of bubble instability. While a higher cooling air rate stabilized the bubble for a high BUR, the bubble was destabilized for a low BUR. The bubble with a high TUR sustained greater aerodynamics forces acting on the bubble surface, resulting in a broader operating range of stable operation. Finally, a numerical simulation using a RNG (renormalization group), k –ε model, and Fluent software was performed to analyze the effects of momentum and heat transfer from the cooling air to the polymer film on bubble instability. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers