Author(s): Andrej Predin; Ignacijo Biluš
Abstract: In this paper we present the results of our experimental analysis regarding the influence of additional flow when added at the radial impeller entrance eye. This analysis was done on both operating and prerotation flow characteristics. The experimental system tested was arranged to operate using air. The additional flow adding system (AFAS) was placed at the entrance eye of the impeller through the guide system, which consists of the spiral volute at the entrance, ring guide pipe (where the guide vanes are placed), and a ring - like hollow at the end of the AFAS. The ring - like hollow was placed near the shroud at the entrance edge of the impeller blades. The guide vanes in the AFAS were placed in the axial direction, so that the added flow had no swirl component. The operating regime was tested, whereby the AFAS was filled by the flow under atmospheric pressure (non-forced loading). A good influence was evident on the operating characteristic. The stable operating range was enlarged and the operating noise decreased. The achieved impeller head and the overall efficiency increased.