A Blade-to-Blade Solution of the Flow in a Centrifugal Compressor Impeller with Splitters

Abstract

The matrix through flow analysis is used to predict the blade-to-blade flow in a centrifugal compressor impeller which contains splitters (half vanes). The presence of solid boundaries in the flow field and the stagnation points associated with it are treated by assuming that the flow around the stagnation point is isentropic. This removes the instability which the matrix through flow method suffers when stagnation points are encountered within the flow field. The splitters in the present work have the same profile with the full blades. Three different geometries are tested. In the first, the leading edge is 3 mm from the eye, the next is 6 mm, and the third has the leading edge at the exit of the inducer. The calculations show that the differences shown between the three cases are linked with different circumferential components of velocity. The geometry, therefore, of the leading edge is of basic importance in the development of the velocity profiles inside the different channels of the impeller. It is also shown that the distance between the eye of the impeller and the leading edge of the splitter does not affect the flow greatly as long as the leading edge is within the axial part of the impeller. The presence of splitters in general is shown to reduce the width of the suction side boundary layer.