In our experiments for NASA, it became clear that some of the particles in the "bins" were being re-entrained into the flow of mixed air. This was proved by using clean air against full bins, and observing that particles came into the new mixture.
In order to test this, I propose adding a straight pipe along the slits. This pipe will be exposed to the same pressure differential as the particle air. It presumably will have lower resistance and therefore faster flow than the helix, so a net flow of air from the helix to the straight pipe should occur. We seek to test the hypothesis that this will prevent re-entrainment and will improve the number of particles removed from the mixed air.
The fact that the straight-pipe air will now be dirtier than the helix air is a valuable fundamental tool. In some cases, that dirty air can simple be piped "outside" of where clean air is desired. In other cases, it can be captured with a settling chamber.
In our experiments for NASA, it became clear that some of the particles in the "bins" were being re-entrained into the flow of mixed air. This was proved by using clean air against full bins, and observing that particles came into the new mixture.
In order to test this, I propose adding a straight pipe along the slits. This pipe will be exposed to the same pressure differential as the particle air. It presumably will have lower resistance and therefore faster flow than the helix, so a net flow of air from the helix to the straight pipe should occur. We seek to test the hypothesis that this will prevent re-entrainment and will improve the number of particles removed from the mixed air.
The fact that the straight-pipe air will now be dirtier than the helix air is a valuable fundamental tool. In some cases, that dirty air can simple be piped "outside" of where clean air is desired. In other cases, it can be captured with a settling chamber.