Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Nose design, air curtains, undertrays, etc.

Otto · 09-20-2022, 05:05 PM

Thanks, Freebeard, that's the sort of input I was looking for but did not find without keywords including electric, etc.

Now that we have a good graphic of the nose air curtain, let's use it to pose some questions:

1. Why not also have a lower nose air curtain, to fair flow under the car's undertray so as to produce faster flow there to get lower pressure and therefore negative lift to keep the car planted via downforce?

2. Why not cant both such guide vanes forward such that they relieve the stagnation point air piled up in front of the car, but also because they're canted forward, to produce some effective thrust, as done by Julian Edgar with his side curtains of Goettingen airfloil design? In other words, use Edgar's curtain airfoil idea not just at the sides, but also top and bottom? See the video below, and ask yourself if this concept might also apply to upper and lower surfaces, thereby increasing the potential for reduced drag and increased thrust.

https://www.google.com/url?sa=t&rct=...a0M2n07TUagAwA

From Edgar's video, it appears the side curtains are ~30-40% of the total leading edge surface area where stagnant nose air has to whip around the body up, down, or sideways. He reports substantial decrease in drag and some bit of thrust from just the side curtains, so adding upper and lower curtains might double or triple the total aerodynamic benefit.

Further, NACA, NASA, and a slew of other researchers have data on suitable leading edge geometry, including when coupled with leading edge slats or guide vanes. Hoerner's book Fluid-Dynamic Drag is the bible of aerodynmicists, and discusses guide vanes on p. 3-26m noting that such vanes reduce drag on a two-dimensional body by a third to half.

Thoughts?

09-20-2022, 05:05 PM	#9 (permalink)
Otto Master EcoModder Join Date: Mar 2008 Location: USA Posts: 568 Thanks: 1 Thanked 73 Times in 58 Posts	Thanks, Freebeard, that's the sort of input I was looking for but did not find without keywords including electric, etc. Now that we have a good graphic of the nose air curtain, let's use it to pose some questions: 1. Why not also have a lower nose air curtain, to fair flow under the car's undertray so as to produce faster flow there to get lower pressure and therefore negative lift to keep the car planted via downforce? 2. Why not cant both such guide vanes forward such that they relieve the stagnation point air piled up in front of the car, but also because they're canted forward, to produce some effective thrust, as done by Julian Edgar with his side curtains of Goettingen airfloil design? In other words, use Edgar's curtain airfoil idea not just at the sides, but also top and bottom? See the video below, and ask yourself if this concept might also apply to upper and lower surfaces, thereby increasing the potential for reduced drag and increased thrust. https://www.google.com/url?sa=t&rct=...a0M2n07TUagAwA From Edgar's video, it appears the side curtains are ~30-40% of the total leading edge surface area where stagnant nose air has to whip around the body up, down, or sideways. He reports substantial decrease in drag and some bit of thrust from just the side curtains, so adding upper and lower curtains might double or triple the total aerodynamic benefit. Further, NACA, NASA, and a slew of other researchers have data on suitable leading edge geometry, including when coupled with leading edge slats or guide vanes. Hoerner's book Fluid-Dynamic Drag is the bible of aerodynmicists, and discusses guide vanes on p. 3-26m noting that such vanes reduce drag on a two-dimensional body by a third to half. Thoughts?