STUDY OF DIFFUSERS FOR SUBMERGED PIPE OUTLETS

Abstract

Flow expansions are encountered in many engineering problems. An expansion giving the best performance i.e. the least energy loss during the conversion process from kinetic energy to pressure energy suited to the obtaining site conditions is the most desirable one. A study of diffusers of con-stant area ratio of 4 and overall divergence angle of 32o is presented in this work. The study has been made to find the effect of the boundary geometry on the diffuser performance by testing three types of boundary geometries. One boundary geometry is ob-tained from Gibson's formula, the other from poten-tial flow theory and the third is a straight boundary. The study has also been made at three Reynolds numbers ranging from 2.67 x 105 to 8.61 x 105 to find the effect of Reynolds number on the performance of the diffuser. Quite a number of works done by earlier researchers on diffusers have been reviewed in this work. The present study has been made with alt as the fluid. Time average values of total head and static head have been measured at the inlet section and also at six sections along the duct following the diffuser and the dimensionless velocity and pressure recovery profiles are presented in the spatial form.