Rotor blades of axial fans

Changes in potential flow and wake will have an impact, and blades may also act as sound barriers to strengthen the acoustic radiation generated by the lift pulses on the blades adjacent to the blade row. This effect depends on the ratio of the wavelength of the sound wave related to lift pulsation to the size of the blade as a barrier. In the frequency range where the ratio is greater than 2, the change in radiation intensity due to this effect is the most significant. Therefore, when the upstream and downstream of a noise-radiating blade have the same number of blades, and each blade in the two rows of blades meets a rotor blade at the same time and constitutes a sound barrier on both sides of the source, this effect will be stronger.

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