Fluid Transient and Heat Flows in Screw Viscosity Pumps

Abstract

It is the objective of this paper to investigate the dynamic response of fluid and heat flows in screw viscosity pumps so that their performance may be correctly and easily predicted, the design of the pumps may be improved, and appropriate automatic control devices may be installed on them if necessary. These pumps consist essentially of a spindle threaded with screws working within a closely fitting sleeve. The analytical model consists of a viscous fluid in a stationary groove induced to flow by the sliding of a cover plate. The groove is of rectangular form or a semicircle. The effects of fluid viscosity and compressibility are included to derive transfer functions relating the pressure and velocity variables at the two cross sections of a line and the velocity of the sliding cover. The response of the fluid temperature to a deviation in the plate temperature or heat flux is also investigated. Numerical results are obtained for the frequency responses of the fluid velocity, pressure, and temperature for a screw viscosity pump with large-width rectangular groove. A phenomenon of resonance in the amplitude ratio and phase shift is disclosed. Screw viscosity pumps to which the analytical results apply include the screw pressure machine and the screw extrusion machine.