Pressure drop for molten polymer flow through tapered dies

Some approximate equations for the calculation of pressure drop for polymer melt flow through slightly tapered dies are presented. These include equations for pressure drop in a truncated cone, converging flat plates, and a converging annulus. The predicted values obtained from these equations are compared to the results of a finite element simulation for two‐dimensional flow of a power‐law fluid and some experimental data available in the literature. It is concluded that the approximate equations can be used for pressure drop calculations for dies of small taper angles and when entry, exit, and viscous dissipation effects are negligible.