Effect of Boundary Layer Fences and Casing Treatment in a Centrifugal Impeller

The paper presents the results of experimental investigations carried out on an unshrouded impeller of a centrifugal compressor to explore the possibility of improving the exit flow condition by the use of boundary layer fences and casing treatment. Eight different locations of fences were tried on the impeller vanes and hub surface. The boundary layer fences placed on the vane suction surface resulted in improvement of the exit flow condition. A combination of grooves and the fences on the front casing cover near the inlet and tip of the impeller was also investigated.