What is leading to the breakdown of this FSAE FW Endplate vortex?
This is the front wing endplate of a FSAE car (USA rules) (straight line, 60kph).
This is a good number of iterations into a re-design. The inherent problem, in different locations to different extents, is preventing any vortex shed of the lower endplate/footplate from blowing up and dropping additional loss down the length of the car and decreasing the effective span of the front wing (ie preventing mass flow under the wing being significantly reduced with large blockage from blown up vortex). There is a lot of performance in the wing profiles from this, along with some additional load from the suction on the footplate.
This is what I have developed to so far. My intent is to start by spreading the vorticity across multiple edges/ reducing the pressure gradient over any single edge (bottom of endplate, outboard footplate curl, and slightly from the vane).
So far, somewhat irrespective of which way, I go, I continue to get this formation of loss and pink helicity on the outboard underside of the curl, which eventually blows up and compromises everything else.
I would like some help in understanding, aerodynamically, what are the driving factors in the flow field causing this, so that I could try to create and modify the geometry to prevent/mitigate it.
Thoughts so far:
- Should I stop the channel from expanding in Y as it goes downstream/should I make it more circular?
- I dont know if this will actually change this issue, because I think regardless of the angle it sheds at, there will be some kind of asymmetry as to where the core is sitting, and pressure gradient pulling it inboard anyway?
- Should I open up a sort of slot gap on the top of curl halfway, as it starts to form?
- example on ferrari 2013 FW
- Have tried this on some older wings (1, 2) and not super convinced, as any loss of the trailing edge didnt seem to work nicely with the start of the second slot - although i do have a discontinuous outer edge here
- (maybe not directly relevant) but I should make the vane longer, to keep feeding some more helicity downstream
I quite a lot of experience in surface design, so ability to make any geometry is not really a factor.
The only possibly relevant restrictions realistically are:
- Dont want to change E1 and E2 (no new tooling on those)
- Front wing width cant go further outboard than centreline max of front wheel (unlike EU rules)
- Limited to Z250 (no higher than wing already goes)