Quote:
Originally Posted by Phase
I could also tuft test it right too? Apparently some people complained about the Prius being too steep and would have flow separation but didn’t when it first came out.
Could anyone do a quick drawing or mock up of how I would extend the roofline then for Lower drag in my Ioniq?
|
Let me share some cautionary information from: MODIFYING the AERODYNAMICS of YOUR ROAD CAR: ( paraphrasing )
1) It is very hard to see trailing vortices. page-19
2) C-pillar vortices are linked to separation. page- 91
3) Flow separation at the trailing edge of the roof explains low base pressure. page- 79
4) Low base pressure explains high drag. page-80
5) A way in which a spoiler can reduce lift and drag is by simply promoting flow reattachment of separated flow. page-195
6) A spoiler can increase pressure on top of the boot and backlight. page-195
7) High base pressure explains low drag. page-80
8) raising the upper body's trailing edge up to the reversal point eliminates vortices, eliminates separation, decreases lift, and lowers drag. page- 19
-----------------------------------------------------------------------------------
If Hyundai's aerodynamics and CFD team has succeeded in establishing the reversal point with the trailing edge of their OEM spoiler, then, any modification should proceed from this optimized location, and along the imaginary pathway it implies.
--------------------------------------------------------------------------------------
Tuft testing, not revealing longitudinally-attached vortices, could easily deceive an investigator, who misinterpreted tufts, aligned from separation-induced downwash, to equate to 'attached' flow. Tufts pointing 'rearwards' are no 'proof' of attached flow. This is an issue for ANY vehicle with a factory rear spoiler.
Hermann Wurst's 'solution' to these issues should, in my opinion, serve as the gold standard for proper aerodynamic problem-solving.