underbody tunnels

[j_type]

has anyone ever seen a tunnel structure underneath a car. as in a cylinder (however flattend).
i dunno how to explain what im talking about well.
but the air moving through the pipe (underbody tunnel) would have a resultant force for this to have an effect.

if youve seen one, has anyone got any pics?

you help is much appreciated.

[j_type]

has anyone ever seen a tunnel structure underneath a car. as in a cylinder (however flattend).
i dunno how to explain what im talking about well.
but the air moving through the pipe (underbody tunnel) would have a resultant force for this to have an effect.

if youve seen one, has anyone got any pics?

you help is much appreciated.

[RiNaZ]

are you talking about the diffuser? The recent UTA cars should have it ... check out their websites. I think UTA has been having underbody works since early 2000

[KevinD]

yes we run an undertray with two tunnels. i think i have pictures i can post up when i get home, but for now i would get an automotive aerodynamics book and read up on it.

[KevinD]

here this is the best picture i have on my computer. it is of out 04 car. you can see the undertray has the tunnel running along it and near the end it flares up.

[Marimvibe]

There are a few decent papers available on diffusers as well, by Kevin Cooper out of NRC in Canada and by Zhang at University of Southampton (I think.) Zhang's are written by his grad students but are more in depth and provide more insight into the flow physics; the Cooper papers are a much broader survey type.

[NetKev92]

Look at

www.mulsannescorner.com

The Audi R8 and the Nissan prototypes have a lot of good undertray pictures of real cars and windtunnel models. I haven't read the aero portion of the FSAE rules recently enough to suggest how applicable some of the methods would be. Most FSAE courses though are made to keep the speeds relatively low compared to what you'd see on a full-scale road course.

Downforce will increase with the square of forward velocity, so unless you keep the vehicle moving quick, you won't get much downforce. Below 50 mph, I wouldn't bother at all. 60 to 70 mph is the point where most full-size cars start to feel the benefit.

[Hotlips]

See Hucho et al "Aerodynamics of road vehicles"
Available from SAE publications.

Good luck,

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by NetKev92:
Below 50 mph, I wouldn't bother at all. 60 to 70 mph is the point where most full-size cars start to feel the benefit. </div></BLOCKQUOTE>

There's a ton of money being spent making road bicycles produce less aero drag- and they spend most of their time in the 15-30 mph range. Aerodynamics are not neglible below 50mph. Debatable on an FSAE car? Sure, but not negligible.

[Jersey Tom]

Aerodynamics is one of the most hand-wavy parts of Formula SAE. Especially in our program. Hopefully that will stop now.

Most full scale cars feel the benefit at 60 to 70mph.. and we're far from a full scale car.