gdogg371 wrote: ↑29 Mar 2017, 16:04
A limited amount of ground effect with a simplified front wing seems like an obvious way of improving close quarters racing.
It is not obvious at all. Several studies using both cfd and wind tunnel all point towards the same direction:
- There's a reaward motion of the COP leading to understeer, however this one is due to the collective effects of the wake on front, rear wing and diffuser
- The front wing mostly suffers from the wake structure and as such experience very different effects depending on both longitudinal and side position relative to the leading car. those effects range from a severe decrease of downforce/drag ratio due to a vast increase in drag while downforce is unafected to downforce loss to downforce increase (sic!).
- The rear wing and underfloor suffer from the loss of velocity potential, i.e the draft. Their downforce/drag ratio stays about the same (that is they lose both downforce and drag). The peak suction from the diffuser is severely decreased because ground effects are very sensitive to the veloticity potential.
- Tyres impact a lot the wake structure
- the upwash of the wake by the rear wing (of the leader car)is fundamental to clean the air behind the leader car. As such an full ground effect car creates a wake with less draft but the wake stays close to the ground along along a very long distance resulting in similar losses than a full wing+diffuser car
All of those characteristic are worsened by wings and diffuser operating near their stall angle.
Now, let's just look at F1:
- The aero parts are definitely running near their max angle of attack
- Despite the uniformisation of the rules, subtle differences in wake structures make other cars suffer even more.
Simplifying the front wing imho will do nothing but to have a less efficient wing with even less flow conditioning at the back and more flow spoilage. Do not believe one bit that a simplier wing is more tolerant to wake!
Going for full ground effects is neither the answer in itself.
So why it does work for some series? Simple, all those series have something in common: they are single make. You still suffer, but everybody has the same wake structure. In addition they do produce less downforce than F1, operate farther from their limits and the speeds at which the car go are lower so loss of grip is less detrimental to competition.
Imho the solution is via active aero. For front wing that would mean moveable flaps or shape morphing to accomodate for the wake structure. For rear wing and diffuser, that would mean using fans to recover the velocity potential lost.
Of course, all of that with the hypothesis that we want F1 to be as fast as it is..which is impossible with tyres alone.
Ref:
Newbon J et al, CFD Investigation of the Effect of the Salient Flow Features in the Wake of a Generic Open-Wheel Race Car, 2016
Zhang X et al, Turbulent Wake behind a Single Element Wing in Ground Effect, 2008
FondTech, OWG study, 2007 (not published)
BMW Sauber, CFD development of the BMW-Sauber 2009 aerodynamic proposal for the OWG, 2007
Goodwind A, AERODYNAMIC LOADS UPON A LOW ASPECT RATIO WING WITHIN A WHEEL WAKE, 2007, Msc Thesis
Soso MD et al, Aerodynamics of a wing in ground effect in generic racing car wake flows, 2005