The Influence of Flow Rate on the Wake in a Centrifugal Impeller

Abstract

Three-dimensional flows and their influence on the stagnation pressure losses in a centrifugal compressor impeller have been studied. All three mutually perpendicular components of relative velocity and stagnation pressure on five cross-sectional planes, between the inlet and outlet of a 1-m dia shrouded impeller running at 500 rpm were measured. Comparisons were made between results for a flow rate corresponding to nearly zero incidence angle and two other flows, with increased and reduced flow rates. These detailed measurements show how the position of separation of the shroud boundary layer moved downstream and the wake’s size decreased, as the flow rate was increased. The wake’s location, at the outlet of the impeller, was also observed to move from the suction surface at the lowest flow rate, to the shroud at higher flow rates.