2010 Mazda3 Hatchback aerodynamics animation (& discussion of factory optimization)

[womprat]

This animation from Mazda is quite interesting. I've been doing reading up on aero, looking to do some mods and found a video that was interesting.

First up note the grille area reduction.

http://www.youtube.com/watch?v=KbGgjSBkZ3A

Second (about 0:40), they demonstrate air swirling up over the wheel in the front wheel arch and imply that wheel well deflectors stop this to some extent. The accepted wisdom from my reading on ecomodder is that the deflector prevents air hitting the tire and making a high pressure area, but this points out that air would naturally flow up over/around the wheel to exit at the rear of the wheel arch.

Note the wheel deflector has a opening to let some air through!

I don't quite get the treatment of the A-pillar vortex though, is that just a smoothed out edge? They seem to imply they've wiped it out with a simple modification.

A little food for thought hopefully. Gives me a few ideas of what to do.

[alohaspirit]

cool stuff

like the fast and furious version of aerodynamics

i really like how the add-ons affected the flow

but the smiley grill still looks funny

[dcb]

lol, many of those "flow lines" look more like an artists wishful rendition than of actual flow lines. calling BS on the smoothly reattached tailcone lines for sure. And the wheel wells would have a lot more turbulance. And whatsup with the windmill spoke wheels? not really an accurate representation imho.

[gone-ot]

...it's "animation" vs. "instrumentation"

[dcb]

it is "lies sprinkled with bs" vs accuracy.
spec lists it as a cd of .31, that would suffice for most of us instead of fakeness.

http://images.mazdausa.com/MusaWeb/f...5DoorSpecs.pdf

for comparison basjoss estimates he is at .17, the new prius is listed as .25

[2003protege]

Still gets 29mpg EPA Highway......

BUT THOSE FLOW LINES ARE PURTY!!!

[aerohead]

I think it's a reasonable portrayal of the real world.
I especially enjoyed the wake imagery.I could easily visualize the gap-filled trailer erasing the entire wake for a composite sub-Cd0.12 range-extender.
Thanks for sharing that!

[Frank Lee]

Seen it before; it's on here somewhere.

[MetroMPG]

Coincidentally, I just read an article about the aero changes Mazda made between the two generations of the 3, and it addresses several of the things "represented" in that video.

From: 2010 Mazda3 5-door - Top Speed ....

• 0.30 - 0.32 - previous generation's drag coefficient (depending on body style and tire size)

• 0.29 to 0.31 - latest generation's Cd

Regarding the grille...

Combining the two medium-sized grille openings used previously into one larger opening also pays functional dividends. Frear explains: "Shifting the air-intake lower on the car increases the pressure of the flow. As a result, the actual grille opening is 20-percent smaller than what was necessary with the previous generation MAZDA3. Most of the air is routed over the hood or around the sides of the car

Also...

Subtle reshaping of the front bumper beam greatly diminishes the turbulence of air passing through the grille. Several speed flaps located in the radiator shroud automatically open at highway velocities to allow some air to bypass the cooling fan.

That one's not clear to me. They don't seem to be saying the car has an active grille, which would keep extra air outside the engine bay in the first place.

They seem to be saying that when pressure rises high enough, the flow that already got through the grille is passively re-routed from highly tortuous "path A" to somewhat less tortuous "path B".

Regarding the sedan....

"...the elevated decklid surface is both an aerodynamic aid and a means of maximizing trunk room."

Regarding the A-pillar & other details...

Wind tunnel testing revealed that small deflectors located near the front tires and subtle adjustments to the upper-forward corners of the A-pillars, outside mirrors, windshield wipers, and taillamps also helped smooth air flow along the sides of the car. The net gain was a six-percent reduction in wind noise.

And they finish with an unsupported flourish...

In terms of aero performance, the new MAZDA3 is one of the most efficient entries in its segment.

That's all stuff from a Mazda press release.

Funny they don't mention the underbody panels shown in the video. Wonder if they left them off the production version...

[Frank Lee]

That one's not clear to me. They don't seem to be saying the car has an active grille, which would keep extra air outside the engine bay in the first place.

They seem to be saying that when pressure rises high enough, the flow that already got through the grille is passively re-routed from highly tortuous "path A" to somewhat less tortuous "path B".

Re: bumper beam: they are talking about streamlining the beam behind the grille so that flow behind the grille and before the radiator is "cleaner".

Re: speed flaps: they are nothing new; IIRC I've seen 'em on cars from the '70s. They are light, flimsy rubber flaps behind the radiator that hang like mudflaps; at low speeds they are closed and also if the fan kicks on they are sucked closed so as not to draw air from the engine compartment. Of course then at speed when the flow velocity through the radiator gets high enough they open, just like reed valves.