Since the conventional turbofan pressure is not generated in the central portion of the fan, but by the rotation of the fan blades appear. Therefore, regardless of how high speed, there will be no wind at the bottom of the axis. But it is at the core of the heat where the axis of the fan is the main source of heat. Such situation creates traditional "Axial Fan" handicap: motor being blocked, airflow trouble to the central site, resulting in "blind spot". Blind spot results in high temperature radiator core portion, affecting the overall cooling effect. To solve this problem, a centrifugal fan is manufactured runoff.