I just found this thread, quickly zipped through the pictures and thought I might as well post my variation. I came up with this a little while ago out of the blue to solve forced air cooling and had no idea that many other people had done the same thing. Oh well...I guess great minds do think alike.
I have 3 hubs I want to force ventilate like this.
People have shown a diagram where the intake side has the air separator and the exhaust side does not. I came up with virtually the same thing on my own, but I separate on the exhaust side.
1. Drill holes in a ring towards the center of both covers and inline with the ducted fan exhaust side.
2. Put a ducted fan in between the spokes inside the hub as has been shown previously.
3. Attach a shallow bowl shape to the exhaust side of the fan that covers all of the exhaust holes. Position it very close to the inside of the side cover. The idea is to have it close enough that you get 90% air flow out of the shell and only a little leakage back into the motor cavity. The smaller the gap between the bowl covering the exhaust holes and the shell side the better! But obviously they can't actually touch.
4. Create an internal duct that redirects the suction side of the fan into the exhaust side of the motor through another internal spoke hole.
5. Close up any remaining internal holes through the motor.
The effect is you draw air in from one side of the hub motor (intake side). There is no air flow path except through the stators and magnet gap at the perimeter of the motor since all other air flow paths are now blocked. You get lots of swirling air inside the intake side of the motor picking up heat before it passes through the stators. Air is sucked through the stators and into the exhaust side of the hub motor. It is then redirected through that duct and into the intake side of the fan. Hot air exits the exhaust side of the fan and out through the bowl and exhaust holes. In theory, the intake side will be all cool air coming in, sucked through the stators and magnet gap and then into the blower and out the exit holes. There won't be any dead air space inside the motor since the entire internal space of the motor will have air flow through it, but will be forced through the stators since that's the only air flow path. Air flow will have little choice but to enter near the center on one side of the motor, be sucked through the stator teeth and exit on the other side of the motor near the center.
Here's a quick sketch of my idea...and of course I missed something...close off the area around the fan so air can't go any direction but through the fan.
And a few close-ups since it's not so easy to see...