Quote:
Originally Posted by Phase
The pointy shape is just an extension of the originally OEM hard separation edges that Hyundai already tested in the wind tunnel. I didn’t want to alter the rear side shapes because I have no idea how it would affect up wash or down wash or wake shape. I cut the inside shape to add a more stylized sporty look. In all, it’s just an extension of the original sides from Hyundai. The poster board tests with the same shape and duct tape already gave me a 4 extra mpg boost from testing before.
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I'm just saying that, if you have a constant-contour in these 'fins', that, at the trailing edge, there will be a mandatory difference in velocity and pressure, which will introduce vorticity, something which would not occur if you simply made the trailing edge 'vertical', like Koenig-Kamm did in the 1930s.
Hyundai/ KIA / Genesis is going to do exactly this next year on one of their big SUVs.
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' ... angled inward...the airflow remains attached until the trailing edges...the resulting wake will be smaller.' Julian Edgar, 2018, p.131
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' A wide wake does not necessarily imply a low rear end pressure; in fact, the reverse can be true.' Julian Edgar, 2018, p.11
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( Another contribution to drag arises from trailing vortices...) Julian Edgar, 2018, p.11
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' Trailing vortices are shed by angled, upright edges...' Julian Edgar, 2018, p.17
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' The flow separations that lead to a pressure drag can be... inclined separation line flow separation shed vortices with axes roughly parallel to the separation lines with well-ordered, steady three-dimensional flow separation on the rearward surface, inducing a suction which leads to a pressure drag.'
Hucho, 1986, p.59-60, 2nd Edition