This thesis outlines past work on solid-handling jet pumps and reviews both practical and theoretical approaches made by workers investigating jet pumps. It was found that there were no theoretical studies of solids-handling jet pumps although these devices have been, and are increasingly being, used for solids-handling applications. Theoretical studies of jet-pumps, without entrained solids, suggest that the integral moment equations can be used to predict events in the mixing tube. It was considered reasonable to adopt this approach when trying to predict mixing tube events when solids were entrained in the jet pump secondary flow, and equations are developed to include solid material. The solids are assumed to be completely separate from the fluid with no interaction between them. An experimental rig was built with provision to eject air into a pipe, which represented a jet pump mixing tube. The ejected air entrained secondary air which contained polystyrene beads of mean diameter 700 microns. Measurements made included the wall static pressure, air velocity, obtained from measurements taken with a Pitot-static tube, and solids mass flow, obtained from measurements taken with an isokinetic sampling device. Using the information gained from the experimental work, profiles of velocity and mass flow were obtained for up to twelve axial locations. These data were used as input for a computer program written especially to solve the integral momentum equations previously set up. The computer used was an ICL 1906A. The object was to compare the experimental and theoretical axial pressure, velocity and solid concentration changes. It was found that good agreement was obtained between experimental and computed values when no solids were present, but only limited agreement when solids were present. The lack of good agreement is this latter case was attributed to the fact that it had been assumed that the solid particles would, at all time, be at the same velocity as the air, whereas this was not found to be so. It is concluded that this work provides a basis from which others can proceed to provide design data for solids-handling jet pumps; devices which will find increasing use in the future.
|Date of Award||1974|