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Originally Posted by norbert24
Thanks! Now here is my question- if the fins are angled apart, but the outside ones are parallel, then the "channels" between the outer fins and the next ones in would have the opposite effect as the inner ones... ?
Do you see what I mean? If you set it up that way, there is an X degree difference between the inner fins, and then the parallel outer fins create a -X degree difference.
In this example, it looks like there are no parallel outer fins, but they are all angled. But I can't tell for sure.
Thanks for your help with all of this! |
From the picture, I can't tell for sure if they are angled either, but I would say they are parallel, as the outer fin on the right-hand side of the car is inside the inner edge of the rear right tyre.
If they angled, it looks like only a degree or two each would be possible, as there are so many.
Most diffusers I have seen have only a few vertical fins, if any. Some only have partial fins or ribs, if you like.
I guess the important factors to remember are that to work at all 1) the diffuser must be 'divergent nozzle' - i.e. the cross sectional area at the back/outlet must be greater than the cross sectional area at the inlet - where it meets the flat floor 2) the angle of divergence overall, and in any chamber formed by vertical fins, should be around 7 degrees be sure that the flow of air remains attached and non-turbulent, and 3) if there are multiple channels in the diffuser formed by vertical fins,
none of the channels should be converging - i.e. have a smaller scross sectional area at the rear than at the front.
I think that, unless you have some part of the car protruding into your diffuser - like a gear box - you are unlikely to see much benefit from multiple vertical fins. But if you want to know for sure, you need to visit a wind tunnel!