Bi-directional cooling fan

A radial fan comprises a base with a plurality of straight primary blades radially oriented and substantially uniformly spaced around the circumference of the base. A like plurality of splitter vanes are interspersed between successive primary blades. The splitter vanes have a length that is about 50-70% of the length of the primary blades. The inner edges of the splitter vanes are angled to improve airflow through the inlet area between primary blades while reducing the occurrence of vortices and recirculation. The addition of splitter vanes increases the airflow capacity of the fan without any significant increase in operating noise.