4.2.1. Impeller inlet

Hub-to-tip ratio is a key owing to the secondary losses, which occurs in the flow regions near the end walls. The presence of any undesirable circulatory or cross-flows develops on account of rapid and steep flow turning through the blade channel accounting for annulus wall boundary layers. Therefore, impeller hub-to-tip ratio was set at 0.35 within the range of 0.3– 0.6 prescribed in [6].

Mach number at impeller inlet was set at 0.65. Impeller inlet blade angles were setup by PCA Engineer's Vista CCD tool analytical calculations. The inducer leading edge angles are 35, 56, and 63, respectively, with incidences of 11.8, 3.7, and 0.1 at hub, mean, and shroud, respectively. Leading edge of the impeller was defined by an elliptic ratio of 6.
