A centrifugal fan consists of a housing, impeller, rotating shaft, bearing, air inlet, air outlet, and motor. The impeller is fixed on the shaft, and there are many blades on the impeller. The number of blades of different models is not the same, and the shape of the blades of different angles is not the same. There are several kinds of forward bending, backward bending and radial bending. The fan housing is a logarithmic spiral linear volute. When the fan is energized to rotate, it drives the impeller to rotate, driving the gas to continuously flow in and out, and generates the air volume and voltage. With the different shape of the impeller blade, the generated air volume and wind pressure are also different.