An Investigation of the Influence of the Boundary Layers on the Performance of Centrifugal-Compressor Impellers

Abstract

Under certain conditions, poor performance of a centrifugal compressor can be attributed to irregularities in the velocity distribution at the entrance of the diffuser which may be caused by separation of, or secondary flows in, the boundary layers on the impeller surfaces. A detailed analysis is made of the boundary layers on the blade-suction surfaces and the shrouds of several radial-flow test impellers. Measurements of the discharge-velocity profile with a hot-wire anemometer show that the analysis successfully predicts the relative performance of the impellers. The installation of boundary-layer fences is shown to cause some reduction in the amount of secondary flow in the shroud boundary layers.