Monday, March 02, 2015

McLaren front-wing vortices, circa 2003

Academic dissertations conducted in association with Formula 1 teams tend to be subject to multi-year embargoes. Hence, Jonathan Pegrum's 2006 work, Experimental Study of the Vortex System Generated by a Formula 1 Front Wing, is somewhat outdated, but might still be of some interest to budding aerodynamicists.

Currently an Aerodynamics Team Leader at McLaren, Pegrum's study concentrated on a front-wing configuration not dissimilar from that on an MP4-18/19 (2003-2004).

A constellation of four co-rotating vortices were created: (i) a main bottom edge vortex, generated by the pressure difference across the endplate due to the low pressure under the wing; (ii) a top edge vortex, generated by the pressure difference across the endplate due to the high pressure above the wing; (iii) a canard vortex, a leading edge vortex generated by the semi-delta wing ('canard') attached to the outer surface of the endplate; and (iv) a footplate vortex, generated by the pressure-difference across the footplate operating in ground-effect. 


Pegrum shows (in the absence of a wheel, below), that the strongest vortices are the bottom-edge and top-edge vortices, but all four mutually interact in the manner of unequal, co-rotating vortices, undergoing the early stages of a merger.

Now, whilst co-rotating vortices have a tendency to merge, counter-rotating vortices have a tendency to repel. Pegrum highlights the 1971 work of Harvey and Perry, Flowfield Produced by Trailing Vortices in the Vicinity of the Ground, which demonstrated that when a vortex spinning around an axis in the direction of the freestream passes close to a solid surface, it tends to pull a counter-rotating vortex off the boundary layer of the solid surface, (as illustrated below by Puel and de Saint Victor, Interaction of Wake Vortices with the Ground, 2000). 


The interaction between these counter-rotating vortices is such that the primary vortex is repelled away from the solid surface. This phenomenon, of course, is still very much of interest when it comes to the Y250 vortex and its cousins.

4 comments:

Scott Moyse said...

That is very cool. Thanks for sharing!

Gordon McCabe said...

No problem!

Matt said...

Hello,

Great job, thanks for sharing! Would it be possible to get your McLaren wing model by any chance?

I am interested in understanding vortices and having your model would help me to correlate my CFD with what you obtained.

Thank you in advance for your answer.

Matt (http://mathieuhorsky.wordpress.com)

Gordon McCabe said...

No problem.

Unfortunately, I have no McLaren wing models in my possession!