Tested: vortex generators (AirTabs) on a Toyota Corolla

[SmartTrucker]

I'm not sure if it would make any difference and I know it goes against ones driving principles but I'm curious if it would be of more benefit as you go faster.

Maybe test it out going 100km/h or faster??

[tasdrouille]

Third pic in post #21, that's the trunklid during tufts testing without the airtabs on right? How do the tufts looks at the end of the trunklid? Is it just me or the flow reattaches to the trunklid? If so it's evident why you didn't get an improvement with the airtabs. If the flow reattaches without vgs, all you're doing is reducing the size of the arch vortex.

Vgs have an induced drag cost and a potential form drag benefit. They are only worth it if the form drag reduction benefit outweigh the induced drag cost. This cost/benefit ratio is highly dependent on vg design, density and placement.

My feeling, from looking at what's been demonstrated to work on airfoils is that airtabs put form over function.

[MetroMPG]

Originally Posted by roflwaffle

Any chance you could test 'em on top on the trunk near the abrupt drop back there?

How about the sides & rear of a Toyota Sienna minivan w/o roof racks? We're running out of decent testing weather with fall nearly on us, but my sister has one of those, and I'd like to make an effort to look at it.

[MetroMPG]

Originally Posted by tasdrouille

Third pic in post #21, that's the trunklid during tufts testing without the airtabs on right? How do the tufts looks at the end of the trunklid? Is it just me or the flow reattaches to the trunklid?

The middle two or 3 tufts at the trailing edge were swirling a fair amount; the outside ones were turbuent, but streaming mostly aft.

I think I read a comment Phil left somewhere that even a locked vortex takes energy to maintain, so reducing its size should help some as well... though obviously not enough for me to measure on this car with that VG arrangement.

[cfg83]

MetroMPG -

Originally Posted by MetroMPG

The middle two or 3 tufts at the trailing edge were swirling a fair amount; the outside ones were turbuent, but streaming mostly aft.

I think I read a comment Phil left somewhere that even a locked vortex takes energy to maintain, so reducing its size should help some as well... though obviously not enough for me to measure on this car with that VG arrangement.

Here's a dumb question. Airtabs are designed to target the trucking market. Could this mean that the Airtabs are "scaled" to work best with a shipping container? If yes, then maybe you could take the frontal area of a standard-issue shipping container and "downsize" the airtab to work with the frontal area of the Corolla. Here are standard-issue freight container dimensions :

Shipping container standard dimensions

40' Dry Freight Container

External Dimensions
Length: 40'
Width: 8'
Height: 8' 6"

CarloSW2

[roflwaffle]

Originally Posted by MetroMPG

How about the sides & rear of a Toyota Sienna minivan w/o roof racks? We're running out of decent testing weather with fall nearly on us, but my sister has one of those, and I'd like to make an effort to look at it.

What year is it? Even though any 90ish degree angle is good I'd say the older the better since some of the newer boxy stuff has unbelieveably low drag for what it is. For instance there are quite a few sites claiming the new base Tacoma has a drag coefficient of .36, which for a truck is pretty damn good, provided of course it's accurate. Offhand I'm pretty sure that a Sienna would be fine, but some of the stuff they're doing results in normal looking vehicles w/ impressive drag coefficients, and something as crude as a VG may not help something that's already optimized.

[roflwaffle]

Originally Posted by cfg83

Here's a dumb question. Airtabs are designed to target the trucking market. Could this mean that the Airtabs are "scaled" to work best with a shipping container? If yes, then maybe you could take the frontal area of a standard-issue shipping container and "downsize" the airtab to work with the frontal area of the Corolla.

There's mention of the air tab size being roughly the size of the boundary layer, so does the boundary layer vary much between a semi near the back and a passenger car near the rear window?

[TELVM]

A radical kind of VGs on the wing of the Symphony SA-160 aircraft:







There are two of them upstream or each aileron, to retain control through stalls.

[Xringer]

Better for controlling the airplane, but adding drag? Slowing it down? Using more fuel?

[cfg83]

TELVM -

Those look so cool! But like Xringer said, I wish I knew if they "map" to our goal of reducing drag. Speaking as an amateur, "retain control through stalls" sounds like reducing drag.

CarloSW2