Numerical and experimental investigations on non-axisymmetric D-type inlet nozzle for a squirrel-cage fan

In this study, the unique reverse-flow around inlet nozzle of a squirrel-cage fan was numerically studied by computational fluid dynamics (CFD), and non-axisymmetric D-type proposed to inhibit it. It is shown that serious back flow develops at volute tongue when operates low coefficient lower than best efficiency point. The airflow passing blade passages in reverse further crosses impeller, mixing clearance leakage airflow, finally blows into intake chamber near circumferential position 150?. By installing along direction, schemes with different blockage extent were calculated CFD. scheme cut distance 70% its exit-section radius chosen as design comprehensively comparing ratio performance working conditions. CFD results illustrated blowing entrance significantly constrained nozzle, vortex correspondingly disappeared. Experimental data new increased pressure rise under low-flow conditions about 6% barely reduced other points.