When the "Blower Fan" installation guide vane angle θ = 0°, the vanes of the inlet flow essentially no effect, the air will flow into the radial impeller blades. When θ >  0°, the inlet guide vane airflow imports will definitely speed deflection angle θ in the circumferential direction of the velocity, while imports airflow velocity has a certain throttling effect, this pre-swirl and throttle action will cause fan performance decline curve, so that the operating point changes, to achieve "Blower Fan" flow regulator. Centrifugal fan with inlet guide vane adjustment method, a high efficiency and a wide range of performance at part load operation, while maintaining the outlet pressure constant conditions, work flow may vary from 50% to 100% of the rated flow range. Adjust the depth of the greater, the more the provincial power. Such as reducing the flow rate to 60% of the rated flow rate when the inlet guide vanes way than the meter-way power savings of up to 17 percent. In addition, its relatively simple structure, reliable operation, easy maintenance and management, low initial investment. Thus, the project "Blower Fan" adopted to regulate the flow inlet guide vane, is clearly the best way to regulate.