Exit scoops

[joey81]

Anyone tried this before?

The idea is to regain lost suction by making it easier for the clean air below the bell mouth to go up the output pipe.

They're supposed to be curved vanes that guide (or scoop) the spinning air toward the center.   The thin metal strips straightened a few seconds after I turned the DC on.  Now they're just air brakes.  ;D

It seems to work.  Suction improved from 1/2" without the scoops to 2".  And I don't see any noticeable hit in separation (just visuals, no measuring tool)

Also, I just finished my tophat build a couple of days ago.  So, no long-term before-and-after comparison.  :)

[nucww]

see this post
HF DC spiral collector with flow redirection

[retired2]

I've never tried your experiment, but I have a feeling it is doing exactly the same thing as the air straightener I used to improve the performance of my blower.  It is reducing the spin on the air entering the blower, a widely recommended practice by the fan manufacturing industry.