Quote:
Originally Posted by jimepting
Joe's(cwrv892) nice Mini diffuser here:
MINI Cooper S rear diffuser w/ underpanel
has gotten me to thinking of building one for my Insight 1. I think I can achieve the near perfect angle of 2.8-3 degrees. I have a couple of questions to toss out for the experts, neither of which Hucho addresses.
First, does anyone have any good reference material for why one adds longitudinal "dams" to the diffuser, like Joe did? I see it done on Formula 1 diffusers, but we are hardly going 200 mph, so the effect might not be the same.
Second, should I extend the diffuser beyond the bumper? The Insight 1 rolls up the under bumper rapidly at the end and a strange "undercut" area in the underbumper midsection. I don't understand Honda on this, but I'm tempted to extend the diffuser past all that and close in the strange bits, making an abrupt termination.
Any thoughts appreciated.
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Jim,I'm going to 'guess',as I have no real scientific data.
In the race car,the diffuser is operating as a down-force device.
In a wing,'lift' is spoiled if there is any spanwise flow.Some aircraft wings ( especially military)have utilized 'flow-fences' to control spanwise flow.
My guess is that this is the purpose of the 'dams' on the diffuser.
If the race car is overtaken and passed by another race car,the bow and stern waves from the overtaking car will be less likely to destroy down-force in the diffuser if the dams ( fences) are buffering the interference.Without them it could mean loss of rear traction within a curve ,potentially disastrous.
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As to extending the diffuser beyond the rest of the body,it seems that it would become immersed within the turbulent wake and cease to function as a diffuser as it is assailed by turbulence from all sides.