A new approach to optimum design of the two-dimensional blade curves of centrifugal fans was proposed in this study.In the present method,the orthogonal design and the three-dimensional viscous flow field computation were used to determine the optimum controlled deceleration flow in impellers and the blade curves.The blade of a high-efficiency fan was redesigned without changing its design point parameters and the profiles of its hub and shroud.The computational results for the whole fan show that the fan e...