Questions for Phil about shape of baffle plate in the bucket design?
It seems to be a circle with a 240 degree cut out on the circumference of about an inch. Did you try a disk that was simply a 1" smaller radius? Is the 90 degree section against the wall of the bucket necessary? I realize that in some designs that 90 degree section holds the plate in place, but for the bucket design that is not necessary since standoffs are holding it in place.
Did you try different widths of the cut out? 1/2", 3/4" etc.
Did you test your unit with different particle sizes? Sanding particles? MDF dust? Wall board dust? I expect that Dyson spent much time playing with his vortex tube to make it work with a broad range of particle sizes.
I think your baffle is a clever idea. It would be interesting to play with its perimeters.
All your questions (and more) are answered in posts on this forum.
I have found some of them, including the test with chalk dust, but I have not found a discussion concerning the shape of the baffle. In particular, for a bucket or trash can design why can't the baffle simply be circular?
The larger radius allows decoupling of the air above the baffle from the air mass below the baffle.
Without the larger radius, the fast-moving airstream above the baffle "couples" to the air below the baffle, and spins it so fast that much of the debris below the baffle is re-suspended. So much so that it gets another (and another, and another) chance of sneaking out the outlet tube.
I guess I was not clear. Your baffle is not circular since a 90 degrees section touches the bucket side and the remaining 240 degrees is spaced 1 1/8" from the side. Why can't the baffle be circular ( radius 1" smaller than bucket) not touching the bucket at any point?
Actually, the answer goes to your question. To put it simply: Circles don't work as well.