I'm currently designing my own centrifugal fan for one of my projects, everything excluding the motor.
My design is similar to the above just that the outlet is much shorter.
The problem I'm facing is that my fan produces a high pitch noise. Assuming I keep the blades design and the power parameters the same, how can I reduce the high pitch frequency?
To my understanding, the volute casing has a tiny gap at the start of the volute tongue (indicated as Rc), could this be the cause of the high frequency noise?