The investigated axial flow fan investigated in our paper consisted of an advanced axial flow stage, an inlet chamber and a diffuser. The fan stage with high aerodynamic loading and the hub/tip ratio of 0.6 had the design flow and pressure coefficients of 0.60 and 0.83, respectively. The test and computed CFD aerodynamic performance of the axial flow fan and the fan's stage were compared, with acceptable results. Subsequently, analysis of the computed 3D flow was carried out within the wide working range at the rotor blades stagger angle variation of ±20°. Consequence of the rotor blades adjustment is that the blade elements work often at the off-design working conditions with the flow separation on the blades suction and pressure sides. The flow is strictly three-dimensional. Velocity profile distortion and swirl due to the flow separation in the stator blade row decreases the diffuser pressure recovery and efficiency. The diffuser in the axial flow fan environment achieves a significantly higher efficiency in comparison with conical diffuser furnished with ducted-flow inlet conditions due to the increased turbulent mixing. Inlet chamber loss coefficient slightly decreased with the increasing flow rates due to the Reynolds number effect. Core flow in the inlet chamber is without occurrence of significant vortex inducing motion with the exception of the area near the tube where the fan's shaft is located.
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