Although the sirocco fan has the characteristics of high pressure and high quantity flow, there is a problem with the noise which easily becomes loud. The purpose of this study is to clarify the effect of the number of blades on the flow field of the sirocco fan at the maximum efficiency point, using numerical analysis (large eddy simulation). In addition, two sirocco fans with a small number of blades (N=22, 11) were used for this study. As a result of the numerical analysis, there was no significant difference in the characteristics of the velocity vector between the blades at Z/W=0.95 at maximum efficiency point. For Z/W=0.40, it was shown that the area of flow separation is increased and the characteristics of the velocity vector between the blades is greatly different in the case of N=11 as compared with N=22, because the area between the blades is larger.
