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Old 09-05-2012, 08:00 PM   #23 (permalink)
aerohead
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Quote:
Originally Posted by MTrenk View Post
aerohead:
--> Does the flat side really limit turbulence? I think there's enough potential from such a large flat plate to end up creating MORE drag than pumpkins and exhaust bits. I'm completely serious. Flat underpans are required in Formula One to reduce top speeds. :P
--> Diffusers are good.
--> If airflow volume is constant at fixed velocity, then what good does it do to analyze it when cars have changing velocity, not only due to acceleration, but changes is wind speed?
--> Is the golf ball effect really all over the car ever? Because at 20 mph I'd bet money that the hood has laminar attached flow, and a 20 mph golf ball has turbulent attached flow. Perhaps I don't know what you are trying to say.
--> Dimpling the underside of a bellypan would in fact allow you to make a flat one, which is obviously more convenient than turning the underside of your car into an airfoil profile. Let's say that a smooth sphere and a smooth flat underbody are traveling at 40 mph along side a golf ball, and a dimpled flat underbody. Suddenly they encounter wind resistance, nothing is pushing them. We all know what happens to the sphere vs. golf ball (equal diameter). Can we imagine what would happen to the underbodies (same dimensions)?
--> Yes, creasing metal panels, dimpling, or whatever sort of bending manufacturers do is related to many things: panel strength, good looks, airflow, damping properties, etc.

Nevyn:
--> Ask Formula One, they know all about dealing with flat panels and Venturi tunnels under and behind the car, and they use them to their advantage in certain way, while doing their best to eliminate them in other ways. This deals with aerodynamics that I won't know much about until I go to graduate school in approximately 3 years. Some of this stuff is trade secret ya know?

Xist:
--> As for the drawings, I just have to find someone to let me borrow their scanner.
--> I haven't owned a car in about 8 months. I'm paying for my degree by working and playing in the university orchestra for scholarship money. I have just enough for rent and food. Cars are expensiveeeeeeee to keep legal.

freebeard:
--> I'm not really sure what's going on in that diagram... Raised ribs just increase panel strength, but also increase frontal area and probably don't do anything other than just push the air around. I'll try to talk more about sidewalls later, in conjunction with underbodies and front air dams/splitters.

slowmover:
--> It's my opinion that many cooling techniques used on the tops of cars can do well on the bottoms of cars.




Or you could even just use metal mesh type holes. If you cover the bottom of your truck with a belly pan, I think you will be able to achieve the kind of cooling you need. You'll need to go with something heat resistant/something that doesn't get destroyed by heat over time. I've had lots of ideas about trucks and SUV's over the years, so maybe soon I can sit down and draw them out.

oil pan 4:
--> Not really sure I understood anything you meant.

Tried to answer posts bottom to top!
*the panel is a physical barrier which prevents the air access to areas which would be a torture chamber to laminar flow.
*diffusers are good
*we don't need to analyze for different velocities if we're just talking mpg.
*measure the length of your car and tell me what your Reynolds number is at 20 mph.Then go back into your Fluid Mechanics text and tell me what kind if boundary layer you have.Since the golf ball dimples are strictly for transition to a turbulent boundary layer,explain how they will affect your Rn/boundary layer.
*with respect to the balls traveling side by side,if they are scaled to the size of automobiles,both balls will have turbulent boundary layers and separation at 115-degrees behind the forward stagnation points.
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