This might sound like it violates Rule #3, but I haven't been able to find much when searching.

I'm designing a custom centrifugal fan for an air purifier design and a PC case. I need it to be virtually silent with a decent RPM range of maybe 300-400 RPM up to maybe 3000 RPM. The actual fan diameter would be around 230mm.

In both cases, it would be pulling air through a pre-filter and pleated main filter. So I'm trying to prioritize static pressure at low speeds, where it would spend most of its time operating.

For my prototypes, I have a 140mm PC case fan that I disassembled. So it's a tad rough, but it is FAR better than the drone outrunner I was using before. I don't need that kind of torque or speed, so it's far too loud and "notched" for my liking, and with far more poles than probably necessary.

So the PC fan motor is perfect, but I can't find any information on how to source them. I haven't found schematics, either, though I suppose I could just reverse-engineer the schematic on the one I have.

Another option would be to design a custom-wound planar motor, or one where the windings are traces on a PCB. Either way, I would need a custom PCB which could take weeks, so I would prefer to source assembled motors.