Blade-passing frequency

The number of pulses per unit of time generated by the movement of a rotating blade past a guide vane or housing element in fans. This can be, for example, the “tongue” of a centrifugal fan housing or the mounting bracket of the motor hub in axial fans. In addition to broadband flow noise, a tonal component at the blade-passing frequency is usually present in the sound emission spectrum of typical fans and may, under certain circumstances, be a determining factor in the sound level.