화학공학소재연구정보센터
Polymer Engineering and Science, Vol.49, No.10, 1960-1969, 2009
Slip Effects in Tapered Dies
Approximate analytical equations are derived for the calculation of pressure drop of power-law fluids for viscous flow through tapered dies for a wide range of wall-slip conditions. The predicted pressure drop values are compared with two-dimensional (213) finite element calculations to identify contraction angles for which the analytical equations can be used. It is found that the disagreement increases with increase of the contraction angle and with increase of wall slip. At a given flow rate, the pressure drop from the analytical equations is found to decrease continuously with contraction angle, which agrees with the 2D calculations only at small contraction angles. At larger contraction angles, the 2D calculations show that pressure drop increases with contraction angle as opposed to the no-slip case where pressure drop saturates. The existence of a minimum pressure at a specific taper angle depends on the rheological parameters of the fluid and the degree of slip (slip-law exponent), and has scientific importance for the die designer. POLYM. ENG. SCI, 49:1960-1969, 2009. (C) 2009 Society of Plastics Engineers