Plastic Propellant Rheology: The Velocity Profile in Tubular Flow

摘要

The form of the velocity profile of plastic propellant in tubular flow, that is the shape of the deformation across the tube at a given time, has been derived from the flow equation previously established by parallel-plate plastometry. The profile approximates to a cubic curve at the wall, and is flattened exponentially towards the centre. This flattening is caused by the strain-dependence of the plastoviscosity. As the integral of the flow equation has not yet been evaluated, a typical experimental profile (measured at RPE) has been fitted by varying a proportionality constant and a power for the degree of flattening in the equation for the predicted profile. (Author)