Taking a two-stage axial fan with adjustable vanes as the research object

the 3D unsteady numerical simulation was conducted on the axial fan with abnormal installation angle of the second rotor. The abnormal installation angles of two adjacent blade in the second rotor were +9°. The numerical results show that

although the blade's abnormal deflection reduces the static pressure at the fan outlet

the stable operating range of the fan is increased. Stall inception firstly appears at top of the second blade leading edge. Both normal fan and the fan with +9° abnormal angle experience four stages before entering stall: appearance

development

merge and developing into stall cell. The circumferential distribution of the stall inception could not be changed by abnormal blade

and the circumferential distribution of both fans are uniform. Although the evolution time of the stall cell is reduced because of the abnormal blade

but the influence of the stall cell is lower than that of the normal fan. The results have great significance for understanding the complex phenomenon of rotating stall in multi-stage axial turbo machines