AXIAL FLOW BETWEEN ECCENTRIC CYLINDERS

Abstract

Plastic pipe production must use annular dies with eccentricity to compensate for gravity flow in the cooling chamber. Here an algebraic analytic solution is obtained in bipolar cylindrical coordinates for Newtonian and power-law liquids. Dimensionless average velocity profiles around eccentric dies are provided to help plastic pipe engineers determine the needed eccentricity. In curved hose manufacture, the die centerpiece is made eccentric to cause curvature. Dimensionless radii of curvature are plotted to help curved hose manufacturers select proper die eccentricity.

Keywords:

• Plastic pipe extrusion
• Eccentric annulus
• Axial annular flow
• Extrusion shaping
• Curved hose
• Bipolar cylindrical coordinates

ACKNOWLEDGMENT

The authors acknowledge helpful discussions with R. Byron Bird. Chanyut Kolitawong also acknowledges the Royal Thai Government (RTG) for his RTG Scholarship.