"AC Fan" vortex noise is more typical of a type of fan in the industry, there is a certain air to flow turbulence generated when the flow vanes turbulence noise. Air flows through the blade surface due to the pulsation of the turbulent boundary layer turbulent boundary layer generated noise. Because leaf surface turbulent boundary layer off the trailing edge of the blade body vortex shedding generate noise. These types of noise is more difficult to solve, requiring users to master some skills before they can, from the use of the fan, we attach importance to the efficient use of the fans, we can not ignore some of the effects caused by noise. Solve the noise problem is a lot of places new demands raised by users.