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Old 06-06-2008, 05:16 PM   #1 (permalink)
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Another Vortex Generator Application?

I had never heard of Vortex Generator's before coming to this forum. I have no experience with them other than reading everyone else's posts about them. According to many people they seem to work. Correct me if I'm wrong but they help the air flow easier causing the air to flow faster by causing the air to spiral.

If this is the case, could a row of vortex generators be used inside an air intake tube to make the air flow easier and faster from the air box to the engine? Just a theory. Just curious to what others think.

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Old 06-06-2008, 05:26 PM   #2 (permalink)
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Uhm... LINK. I'd be reticent to put anything in my air intake post-filter as if anything got knocked loose it'd break my engine. Theory sounds good, though.

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Old 06-06-2008, 05:30 PM   #3 (permalink)
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That's the selling point behind the 'Tornado' brand 'fuelsaver'. It supposedly makes the air spiral into a vortex.

It does nothing ( except makes your wallet thinner. )

In one test, it actually reduced fuel economy, due to the fact that it is a restriction in the intake.

" Any vortex that is generated is immediately destroyed when the air hits the throttle body ."

So .... if you could create a VG effect inside the manifold, it might do .... something .... but maybe ( probably ) not.

Sorry. It sounds like a great idea though.
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Old 06-06-2008, 05:31 PM   #4 (permalink)
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Quote:
Originally Posted by i_am_socket View Post
Uhm... LINK. I'd be reticent to put anything in my air intake post-filter as if anything got knocked loose it'd break my engine. Theory sounds good, though.

And welcome to the site


Hey ... you beat me to it ! Looks like we are both familiar with the Tornado thingee.
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Old 06-06-2008, 05:50 PM   #5 (permalink)
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Good point
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Old 06-06-2008, 06:33 PM   #6 (permalink)
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vortex generators

I've been reviewing some articles on "turbulators","vortex-generators",and "dimple-tape".All these devices were originally intended for aircraft applications.Placed at the point of maximum camber of a wing or propeller,the device would thicken the turbulent boundary layer,allowing a little additional energy from the free-field to help energize the boundary layer and move the point of separation as far back as possible.If the wing stalled,it would recover sooner.Shock-waves emanating from propellers,with tips near MACH would enjoy reduced pressure gradients at the trailing edges and up to 50-percent noise reduction.There is a penalty in skin friction,however,the claim is that profile drag is so reduced, as to more than compensate.Fuel economy improvements up to 8-percent are claimed for aircraft.Cessna is to use them on wing struts.As to automobiles,the only application I've ever seen designed for,is with notch-back style cars with steep backlight angles.A late 1980s HONDA Accord was the original demonstration vehicle used by the inventor.With respect to an automotive induction system,you might want to bear in mind that the entire system is operating in a positive pressure gradient,unlike a wing or propeller.Ram-air pressure makes sure the air charge makes it's way all the way into the combustion chambers.Should there be any aerodynamic losses taking place within the intake tract,it would be more a consequence of an improperly radiused turn in the ducting.Any elbow of less than a 1-1/2-diameter radius will experience interior wall flow separation and attendant increase in pumping-losses.It would be difficult to imagine that in this day and age,that an improperly configured inlet tract would make it into production.And as I know I'll catch hell from members for saying this again for the thousandth time,when I was at Bonneville,I made runs with no intake tract and no air cleaner and it made absolutely no difference to engine performance at 6,000 rpm.I can't imagine how vortex generators could possibly make a measurable difference inside your air box.If you want to experiment,take meticulous records,measuring everything,especially atmospheric data at the times of your tests.Good luck on the project.
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Old 06-06-2008, 11:33 PM   #7 (permalink)
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Vortex generators exist to trip the airflow from laminar to turbulent to keep it attached over a surface, thus reducing the dead wake and the drag. An air inlet to an engine has no need to keep the airflow attached, it serves no purpose. If the engine needs more air, make the duct to it larger.
The attached pic shows the idea, the dimpled ball has a turbulent boundary layer that stays attached further over the back of the ball.
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Old 06-06-2008, 11:42 PM   #8 (permalink)
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ttoyoda is on the money. Good post.
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Old 06-07-2008, 01:28 PM   #9 (permalink)
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Hi All,

I think the issue with turbulators/dimples/VG's is that the air has to be making a big turn in an area of thin high energy boundary layer. In the ball, the air is pushed out, but for best drag has to make a big change in direction to stay laminar. There is energy in the compressed boundary layer which is used to turn the air, by the dimples.

Similarly with ebdso's finding on the upper third of the A pillar. The air is shooting sideways across the windshield, and has to make a big turn to go laminar down the side of the car. Without the turbulator, this sideways air will just roll, and propagate a big vortex out away from the side of the car as it reenters the slipstream direction. With the turbulator the air tumbles and quickly becomes laminar down the side of the car.

By the way, anybody who says a Prius is good enough aerodynamic wise, was not driving head-on into 30 (thursday) and 50 (friday) mph winds here in the Chicagoland area this week.
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Old 06-08-2008, 12:42 AM   #10 (permalink)
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We have Tread Tape at work for the slippery areas.
Think 10 grit sandpaper with adhesive backing, the opposite of dimples.
What say you for that as a way of keeping the air laminar around the A pillars and down the rear?
Schultz.

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