Diffuser and rear wing interaction

[EVO]

Hey guys,

I'm about to do some research on rear diffuser efficiency, and one way was to add a low rear wing near the exit of the diffuser which creates a low pressure just (behind? or above?) the diffuser exit. Does anyone know any resources where i can look into this further? Or if any of the current F1 teams do this?

Thanks

[RicerDude]

Correct me if im wrong but group c cars of the early 90's used this concept to create a low pressure area just behind and above the venturi exits to improve efficiency.

Allard J2X-C


Peugeot 905

[shelly]

Current F1 rules (from 2009) are built exactly to reduce this interaction between rear wing and diffuser.until 2008 you could see a close coupling between those two elements.
What remains today of this aero concept in f1 cars is the "slotted gurney", i.e. samll wing profilesthat exploiting a rule loophole are placed at the diffuser trailing edge to lower the pressure at the toprear of it.

it could be good if you downloaded 2008 f1 rules and 2009 (or any othere successive year) to see howthe leaglity boxes have been changed and see how big the banned box (where good interaction can be achieved) is.

Then another idea would be compare the rear of a post 2009 f1 with the rear of a 2011-13 gp2 car, or of a 2012-13 f.renault car.They look similar to a f1 (espacially the gp2) but they not constrained by any rule set, and so have much bigger diffuser (i think f.renault has underbody venturis also) and they have a more "natural" positioning of the beam wing, to have cheap and efficient downforce thanks to a close coupling

[godlameroso]

Ideally you just want a diffuser that big, but you compromise by trying to couple adjacent surfaces, it's less effective than one enormous diffuser, but it's more effective than nothing. Truth be told in the game of aero, you'd be surprised how far you can go with relatively little, as long as your shapes are properly designed. Another thing to consider is how the aero at the front of the car can affect the geometry of the diffuser up-wash. Not just by how much downforce the front generates, but by the wake and it's influence on the rear.

If you want to get a rough idea of how to visualize airflow, I suggest you start studying some form of statistical finite element analysis. This is what all that computing power is used for, basically...

[Kiril Varbanov]

Before jumping into extensive theory, I'd certainly ask the OP for more information, as the one given initially is too vague and overly generic.

Read Katz's chapters on how rear wing drives the diffuser, for example, the book is called "Race car aerodynamics - designing for speed".