Sawtooth gurney lip 1

[Dave K]

Recently I saw a race car with a gurney on the rear wing, but instead of the typical constant height lip, the gurney had a "sawtooth" shape. ie /\/\/\/
Can anyone explain this concept, and the advantages/gains that it would provide, over a typical gurney lip?


Thanks

 

[btrueblood]

I remember some undergrads looking into this concept at the U of Washington (Seattle, not DC), back in '87 or so. The idea was that crenellating (fancy term for sawtooth) the trailing edge could reduce the drag at certain levels of lift, at certain Reynold's numbers. Their research showed little effect on relatively blunt-edged crenellations, as I recall.

- Ben T.

 

[jgull]

There's an article in the newest (I think August) Scientific American about a guy who's experimenting with a leading edge with bumps like that. He got the idea from whales which have a lumpy leading edge. He built some mockups and got some rather astounding results. Not only was induced drag greatly reduced, but the stall angle was hugely increased. He thinks it has to do something with creating of oppositely swirling vortices created by each lump the allow the flow to remain attached much longer, and also have some effect in reducing induced drag. Looks like a cool idea that could have some real merit, as the numbers he got from his experiment were not just trivial improvements. It's worth checking out the article if you can.

Jamie

 

[Dave K]

Interesting article, and impressive numbers, and yes its the August 2004 issue.

Now I'm curious what some vortex generators would do, when applied to/near the leading edge of a racecar wing, if they would get the same effect as the whales le bumps.

-Dave
"Everything should be designed as simple as possible, but not simpler"