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Old 02-10-2008, 06:45 PM   #1 (permalink)
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Plant Stand Vortex Generators?

Hello -

I keep looking for off-the-shelf parts that could be used as aero goodies. What is you opinion of these :

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They are "plant stand" triangles that can be snapped off. You basically get 16 for $4, and then it's up to you to use glue or magnets to keep 'em on.

The one on my hood has magnetic business-card tape and a neomodium magnet inside to keep it attached.

I don't think it's an ideal shape. Could this shape be modeled for viability?

CarloSW2

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Old 02-10-2008, 07:48 PM   #2 (permalink)
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You're right that it's not an ideal shape.

To generate a vortex, you need a plane set at an angle to the local airflow.

That plant stand is too stubby - it'll just create random turbulence in its wake. I can't think of anything simple you could do to it that would make it mimic the airtab.
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Old 02-11-2008, 02:08 AM   #3 (permalink)
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MetroMPG -

Quote:
Originally Posted by MetroMPG View Post
You're right that it's not an ideal shape.

To generate a vortex, you need a plane set at an angle to the local airflow.

That plant stand is too stubby - it'll just create random turbulence in its wake. I can't think of anything simple you could do to it that would make it mimic the airtab.
Rats. Stupid plant wins again.

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Old 02-11-2008, 02:36 PM   #4 (permalink)
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I am not a strong believer when it comes down to the effect of vortex generators over random turbulence inducers on road vehicules. Intuition tells me that the net efficiency impact of vortices over induced turbulences is negligible at the speed road vehicules are travelling.

I intend to test this premise in the following months using wool tufts on my 2 cars.
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Old 02-14-2008, 09:43 PM   #5 (permalink)
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Quote:
Originally Posted by MetroMPG View Post
To generate a vortex, you need a plane set at an angle to the local airflow.
the inner VGs on the Evo are not angled.
skewing begins/increases as they near the driprails.
also they are fins, not just dumb tabs,
there is purpose to their shape much like
the airtabs have - versus the much simpler
fuelsavers!
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Old 02-14-2008, 10:03 PM   #6 (permalink)
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Quote:
Originally Posted by 3lr View Post
the inner VGs on the Evo are not angled.
You might have that backwards.

The Mitsu PDF that is often quoted on this topic states that the delta style VG's are angled at 15 degrees to the local airflow direction near the car's center line.

Quote:
...the delta-wing-shaped VGs must be installed at an angle of 15° against the vehicle centerline for the central position, whereas they must be installed at an angle near 0° for outermost positions.
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Old 02-14-2008, 10:59 PM   #7 (permalink)
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You might have that backwards.

sure do, my bad.

the outermost fins are straight (parallel to the centerline of the car) and they angle incrementally as they near the car's center.

back to the point i was attempting to make...
they do not nessecarily have to be skewed.
the shape is paramount and just like propellors
and wind turbines wings which are airfoils
which are much more effective that drag type
devices (like the old tin style farm windmill).
like the gassavers which employ drag type
implements vs the airtabs which could probably
be considered a quasi airfoil.

i do admire the yoghurt cup VG's that someone here
has come up with. definitely my cup of yoghurt

MetroMPG, why have you resisted temptation to play with your airtabs for so long?



The Mitsu PDF that is often quoted on this topic states that the delta style VG's are angled at 15 degrees to the local airflow direction near the car's center line.
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Old 02-14-2008, 11:11 PM   #8 (permalink)
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Mainly a lack of time, I suppose. I spent all of my "tinkering time" building the electric car last year. I didn't do any aero mods or on-road testing at all in my gas car in 2007.

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