Deturbulator tape

[Bman83GL]

Hi folks,

I was doing a review at the SAE site to see what aerodynamic papers I need to catch up on when I ran across this.

Looks like it is still in the developmental stage.

http://www.sinhatech.com/

Bman

[2TonJellyBean]

Wow, a 30% reduction in aero drag by running a strip of "turbolator" tape across the roof above where the front seat passengers sit? How simple is that?

I must give this genius inventor money!!! LMAO

An interesting find though...

[trebuchet03]

I'm ALWAYS wary of aero flow add ons to a semi truck that claim high numbers -- there's not a great deal you can do to the flow that's already on a semi given the extremely high Reynolds number....

Look at that! bring the cD of a van from .5 to .1! Not sure how he validated scale wind tunnel testing - it's very dependent on physical length...

[theclencher]

"weary"- no doubt!

[trebuchet03]

"weary"- no doubt!

Doh! Curse you extra e!

[2TonJellyBean]

The only scientific portion is quantifying how wild the claim can be before it starts tripping even the gullibles' BS meters. :rolleyes:

[Dynamically Aero]

Doh! Curse you extra e!

Enquiring minds want to know ;) , are you being cautious (wary) or are you exhausted (weary)?

If both, and to a great degree, then maybe you're like Elmer Fudd and you're weally, weally, wary weary.:D

[Coyote X]

Foam weatherstripping would be way cheaper and easier to test the ideas with. It worked on my helmet when I was riding my bike a lot so there might be a very tiny gain if you get it placed just right on a car.

Somehow I think it would be hard to measure a change even with a coastdown test but I could be wrong ....

[lunarhighway]

i've come across something similar on the web. turbulator tape seems to be comonly used on gliders and is somewhat similar to vortex generators, although not entirely.

the way i understand these things work is that they're placed just ahead of a sepparation bubble wich is a point where laminar flow seppatates from the wing. the additional drag they cause is smaller than the drag the bubble would cause.
for the turbulator to function this point has to be exactly determined.

there might be potential for this on cars, but the very exact placement and potential to small to measure gains might might make this difficult for most people to implement.

on the other hand this turbulator tape seems to be nothing else than a thick sawtooth patterend tape, so people willing to try might be able to make it themselves. or use the stuff used on gliders if you have access to it.... afterall if you compare the width of your car's rooftop to the span of a glider youd only need a small leftover.

[8307c4]

Just use duct tape, what's the difference?

[cfg83]

Hello -

I found this on the site :

Improving Automotive Fuel Efficiency with DeturbulatorTape
SAE Paper: 2007-01-3458
SAE 21st Asia Pacific Automotive Technology Conference, Hollywood, CA, U.S.A.
5th-8th August, 2007
http://www.sinhatech.com/SAE-APAC-2007-Sinha-%2008-06-2007.pdf

I can't make heads or tails of it. When I went to look at the specific conference event guide, I couldn't find the Sinha paper (EDIT: Found it, see next post) :

“Impacts & Opportunities for the Global Automotive Industry”
http://www.sae.org/events/sales/brochures/APAC.pdf

Here is the organization that is was presented at (maybe) :

14th Asia Pacific Automotive Engineering Conference (APAC-14)
August 5-8, 2007 / Renaissance Hollywood Hotel / Hollywood, California, USA
http://www.sae.org/events/apac/
While the name has changed to reflect a broader audience, the 14th Asia Pacific Automotive Engineering Conference still embodies what the original International Pacific Conference on Automotive Engineering (IPC) stood for. A successful, historic event since 1981, APAC serves as a way to promote automotive engineering development worldwide, choosing this year's theme, "Impacts & Opportunities for the Global Automotive Industry," to focus on five major technology subjects:

* Powertrain Technology
* Driver/Vehicle Interface, Information and Assistance Systems
* Vehicle Design and Manufacturing
* Transportation Challenges in Emerging Markets
* Vehicle Dynamics and Intelligent Control Systems

SAE is pleased to host this premier automotive engineering event with patronage by FISITA.

Here are other events :

http://www.sae.org/events/conferences/groundvehicle/
2007

DoD Maintenance Symposium & Exhibition
November 13-16, 2007, Rosen Shingle Creek Hotel, Orlando, Florida, USA

SAE 2007 Automotive Dynamics and Safety Conference and Exhibition
November 27-29, 2007, Doubletree Hotel Dearborn, Detroit, Michigan, USA
Event Canceled

SAE Brasil Noise and Vibration Conference - NVH
November 28-30, 2007, Florianópolis/SC, Brazil

Congresso SAE Brasil
November 28-30, 2007, Transamerica Expo Center, São Paulo, Brazil
Prospectus*



Here is something interesting. There is a conrference in Anaheim on December 2-5 2007 :

EVS-23: Sustainability - The Future of Transportation
December 2-5, 2007, Anaheim, California, USA
(SAE International co-sponsoring industry affiliate)
http://www.electricdrive.org/evs23/


CarloSW2

[cfg83]

Hello -

Ok, I found the document, so it was part of the conference :

SAE Technical Papers
Title: Improving Automotive Fuel Efficiency with Deturbulator Tape
Document Number: 2007-01-3458
http://www.sae.org/technical/papers/2007-01-3458

CarloSW2

[ChrstphrR]

Just use duct tape, what's the difference?

Hunting around a little:

Seems to be that traditional glider turbulator tapes are raised vinyl sawtooth tape -- with different lengths/frequencies of the sawtooth pattern.

Sinha's turbulator tape looks to be more like a sandwich -- imagine duct tape with a thin plastic set of stand-offs.

1) Bottom layer's the adhesive portion to stick it to the vehicle / airfoil surface.

2) Then there's the "ridged substrate", a set of (equally spaced) standoffs above the adhesive layer.

3) Atop the ridges is a thin membrane -- probably made of mylar, or since the examples are sort of shiny... aluminum backed mylar?

The height of the tape, top to bottom, according to the diagrams he's used in his SAE presentations, is only 50 to 100 micrometres (2 to 4 thousandths of an inch). Erm, I don't think it's much thicker than duct tape would be, really. Sounds a lot more like coroplast scaled down, with saran-wrap on top instead of the hard plastic sheet the one side.

Instead of presenting a "rough" surface, like the sawtooth tapes, or say, sandpaper grit-side-up, the design Sinha's testing seems to vibrate the membrane on top to perturb airflow and/or dampen and remove energy from turbulant flows to make them more calm and laminar, instead of strong, rolling eddies.

[lunarhighway]

after a brief look trought the first document cfg83 posted one thing struck me.
i've been wondering for a while if the windshield to roof transition is't an area that could use more attentiom, and this seems to confirm it somewhat. afterall what good it it to worry about attachement of airflow at the end of the car if it aleady gets detatched at the beginning of the roof. so these turbulators or even vortex generators might work there.
i wich i had a moonroof, that would make tuft testing quite easy.

[cfg83]

Hello -

Here's a pic from the report to illustrate ChrstphrR's commentary :

http://www.sinhatech.com/SAE-APAC-2007-Sinha-%2008-06-2007.pdf
1072

CarloSW2

[cfg83]

lunarhighway -

after a brief look trought the first document cfg83 posted one thing struck me.
i've been wondering for a while if the windshield to roof transition is't an area that could use more attentiom, and this seems to confirm it somewhat. afterall what good it it to worry about attachement of airflow at the end of the car if it aleady gets detatched at the beginning of the roof. so these turbulators or even vortex generators might work there.
i wich i had a moonroof, that would make tuft testing quite easy.

I was thinking of using the AirTabs (http://www.gassavers.org/showthread.php?t=5392) to make the air "jump over" the windshield wipers, but maybe they would work in the same location as the Deturbulator Tape?!?!?

CarloSW2

[lunarhighway]

I was thinking of using the AirTabs (http://www.gassavers.org/showthread.php?t=5392) to make the air "jump over" the windshield wipers, but maybe they would work in the same location as the Deturbulator Tape?!?!?

i remember an autospeed article where they made a full fairing on a first gen prius to cut down wiper noise. it worked for doing that, but no real FE fains where reported as far as i recall. there's a high pressure area that shields the wipers anyway and forms a virtual fairing that smootens out the hood to windshield transition. on the other hand if a similar turbulent bubble would sit on the rooftop that would add frontal area + dragg. so that's where i'd place my AirTabs if i had them.

than again my aerodynamic understanding is rather inclompete so i might be wrong about this

[cfg83]

Hello -

What I find interesting is that instead of the form of the car being "static" in relation to the air resistance, it is instead interacting with the airflow and modifying the turbulence dynamically. If this was designed for airplanes that normally operate at air speed X, would a different version for cars (aka modifying the dimensions of the elements of the tape) work better for cars driving at highways speeds around 65 MPH? Orrrrrrrrrrr, because the membrane is acting dynamically, maybe it operates over a range of speed? Also, gliders are going closer to car speeds, right?!?!?!?

... time passes ...

Answering my own question with this picture :

http://www.sinhatech.com/SAE-APAC-2007-Sinha-%2008-06-2007.pdf - Page 12
1074

From the above, it seems that the glider's airspeed is comparable with cars. I highlighted 51.8 MPH as the "sweet spot", at least based on the above test. On the ground this sweet spot would change (right?!?!?!).

If it did need to be modified, then I think it would need to be modified for even greater top speeds (I was originally thinking the opposite).

Knots to MPH conversion references :

Convert Knots to Miles Per Hour
http://www.flightsimaviation.com/rule-of-thumb/22_Convert_Knots_to_Miles_per_Hour.html

Conversion table for knots to miles per hour
http://www.flightsimaviation.com/rule-of-thumb/22_Convert_Knots_to_Miles_per_Hour.html

CarloSW2

[Hateful]

Just use duct tape, what's the difference?I've got plenty of duck tape on my car but I'm not going to place any on a surface that is already a smooth curved surface, but to deflect air from going under the car and into the wheel wells.
Looks like yet another gimmick to me.

[Dynamically Aero]

In the photo of the Escalade model (http://www.sinhatech.com/auto.asp) in the wind tunnel (click on the photo for a larger image) we can see the deturbulator strip across the front of the roof just aft of the windshield. Do you think the tape going across the hood to secure the model has any measureable effect on the aero?

We've seen photos of vortex generators on the sides of vehicles; might deturbulator strips be beneficial there, too? If so, where on the sides do you think would be most effective?

[sonyhome]

If I understand right, these tapes are ridged to vibrate with the wind pressure...

I suggest sport tape for experiments: It is fabric, very cheap and comes off easily. Duct tape is just slick. I don't have time for these experiments, as I will first pursue other options.

[cfg83]

sonyhome -

If I understand right, these tapes are ridged to vibrate with the wind pressure...

I suggest sport tape for experiments: It is fabric, very cheap and comes off easily. Duct tape is just slick. I don't have time for these experiments, as I will first pursue other options.

I was thinking of the model RC airplane thin plastic sheet rolls that are used for the skin. One problem I see in making your own is figuring out the right tension for the skin to vibrate.

How would you test a homemade version? The oil slick test?

CarloSW2