Plasma drag reduction
 

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Food for thought...



Freebeard mentioned plasma actuators in another thread. I recalled reading about the effect some time ago. Searching on the web for more info, I came across this.

Technology | Plasma Stream

There are good videos in the link showing the effect.


Using plasma actuators to reduce drag in the future looks to be not only possible.

But, a glowing reality...

:cool:


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back to the future

The discussion pre-dates me; bondo in 2012: http://ecomodder.com/forum/showthrea...rag-20309.html

Cycle's thread from last July: http://ecomodder.com/forum/showthrea...ion-32407.html

I found an article in Popular Science last November (http://ecomodder.com/forum/showthrea...rag-20309.html) but the mention seems to have killed that thread.

The progression as I have followed it was the Brown-Biefeld effect in UFO literature to the ionized exhaust gasses of the B-2 bomber to, apparently, 18-wheelers on the freeway any day now. It's a crazy world.

The graphic in the link suposses a 15% reduction at the back of a truck box. Seems like it should be more. I wonder how much energy it takes to produce the plasma?

http://plasmastreamtech.com/wp-conte...le-savings.png
http://ecomodder.com/forum/member-fr...dynamics-c.jpg

It take a high voltage, high frequency signal to open the plasma channel, but I think it takes less to maintain it. Could be wrong.

Power needed is very low. Our preliminary testing shows an average power consumption of 1 watt for 1 meter long actuator .

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PranayBajjuri

Thanks for chiming in.

That is a very low power requirement.

It's always nice to have a representative or in this case "co founder" of the company to answer questions.

Any idea when it will be available...???


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Preliminary on-truck testing is planned for August and planning to have a product for aft portion of the trailer (eTail) by early 2017.

As August is winding down, I wonder how the testing went.

Are things on track?

Deflector shield on full; engage warp drive?

http://newatlas.com/truck-aerodynamics-fuel-efficiency-plasma/48646/

As opposed to a ring-vortex at the rear, this uses 'airtab'-like actuators to create jets at the front. I surmise the effect is similar to a serated edge or fences.

IMG doesn't want to display, but it looks like a stack of tiny headlights.

The video in the last link does a good job of explaining the concept.

Electric wind vortex generator reduces drag on trucks
https://www.youtube.com/watch?v=8zQokKKWBLg

Soo...we're talking about electromagnetic golf ball dimples?

We're talking about 'golf ball dimples' that can be turned on and off in microseconds. :thumbup:

I think the force field analogy fits best, but it's micro eddies or small vortexes of disturbed air forming a protective film or barrier which allows passing air to pass more easily.

Golf ball dimples, shark skin etc.............all depend on the passing fluid (air/water) to initialize the event.

Dimples are passive, this thing is active.

seems suspect I think I will wait and see on this one

wait and see
 

That's my plan also.
Road vehicle aerodynamics requires a turbulent boundary layer to control flow separation.The kinetic energy fed into the boundary layer helps pin it against the body,preventing it from migrating forward to the body's zone of minimum pressure (at the windshield peak) and rolling up into eddies,then full-blown turbulence and separation.
A plasma adjacent to the body surface might ruin the whole feedback system.
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Aircraft and aquatic creatures have fineness ratios which prevent flow separation in the first place and their drag is governed by surface friction or shock wave drag for the fast aircraft.
Not so for automobiles.
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If I were gonna consider plasma drag reduction I'd look to high-speed trains whose boundary layers,according to Hoerner, can be thicker than the frontal area of the train itself.

I guess I need to wrap my head around this. The parallel copper bars on the tail I can see accelerating(dragging) the air rearward, but the U-shape virtual air tabs on the front must act differently. If, as you say, at all.

I won't post this Yoututbe video since it's off-topic but it's findable;

He describes plasma windows (for the muzzle of a rail gun), and towers that are a hollow tube supported by the flow of plasma dragging the tube upward.

I guess I'm a fan of Isaac Arthur, and plasma.

virtual air tabs
 

5% mpg on an 18-wheeler is worth going after.If the device can mimic a VG it could help mitigate some of the damage from crosswind separation.
*The effect would have to be like an optimized VG.
*The system would have to detect the apparent wind.
*Then 'position' the effect as a function of the apparent wind.
*The effect would have to modulate as a function of angle of attack and boundary layer thickness.
*With something like a scanivalve,cited laterally,where the mean flow intensity could be identified,this information fed to a CPU could interrogate a RAM look up menu and choose the best solution for the location,frequency,and amplitude of the effect based upon prior lab testing parameters programmed into the RAM.
*There wouldn't be a drag penalty for 'physical' VGs hard mounted at the nose.

https://upload.wikimedia.org/wikiped...d_p1230157.jpg
https://en.wikipedia.org/wiki/Pitot_tube

I've been thinking that the drip rail down the front of the doors on a VW bus is well within the frontal area. A serrated Gurney flap there would be exposed on the leeward side and could have a similar effect if it were sized appropriately — maybe 1/2" to 1 1/2" serrations? Worth a Photoshop?

We can all relate to fans moving air and requiring energy to do so right???

Anyone here who does not believe a fan needs to be plugged in, using energy to turn a motor, which turns the fan blade, that makes a certain volume of air move??? Raise your hand now, and then quit reading because you're too dumb to comprehend anything.

So, if a fan requires energy to move air......we can assume that causing air to move requires power.

A truck moving through still air is going to cause the air to move, right?? Air needs to be pushed up and aside. A lower pressure area behind the truck is going to need to be filled in, causing air to rush in to fill the void so to speak. The air moving up and sideways is going to push the air beside and above the truck for tens of feet sideways and up, and the air will swirl about for many seconds after the truck has passed, seeking to be still again. Anyone driving behind a truck on a narrow road sees this happening on the grassy fields beside the road and the leafy trees overhanging it. All this jostling of the air is no different than a fan, the air is being forced to move, and how much it moves is the energy required to keep the truck moving. That is what drag is. It is the energy required to make still air move.

Please, anyone, enlighten me on how this concept of plasma makes the air move less?

2nd paragraph is unnecessary.

Plasma actuators make the air move faster, locally; unless I'm too dumb to comprehend anything.

concept
 

It looks like the authors are trying to create the effect of VGs to mitigate the crosswind-induced separation bubble on the leeward side of the vehicle.
http://i1271.photobucket.com/albums/...titled15_7.jpg
During calm conditions the 'VGs' aren't 'there',and there's no drag penalty as you'd have with say AirTabs.
For them to work though,they need to 'move' around on the body,in accordance with a fluid battle field of transient flow separation,as a function of degree of yaw.

https://www.newscientist.com/article...ound-to-space/

I hate barely tolerate the New Scientist's dynamic, unquotable PHP, but if you Inspect Element you find:
And I can get the picture from Google Images:

https://d1o50x50snmhul.cloudfront.ne...11-800x533.jpg
https://www.google.com/search?q=plas...6SD-UJRtJ_bkM:

Answering myself to bump the thread. This may be important.

https://arxiv.org/abs/1609.04054
First problem seems to be it's deafening. :eek:

https://www.youtube.com/watch?v=U5PYzGgHx14

I am gearing up to give this a go.

I have copper tape and kapton tape to create the plasma generators and as a power supply i have the module from a tazer and the electronics of ozone generators (they create plasma which creates ozone)


Would adding these generators to the wheel wells be beneficial?

https://proxy.duckduckgo.com/iu/?u=h...png&f=1&nofb=1


And what is an initial good design for the rear of the car?

Awesome! But now you know the joy of being on the bleeding edge.

The only solution/application I've seen is the rear of box vans. They're a special case aerodynamically, with enough fineness ratio to have unseparated flow at the rear. They are used to reduce the cross-section of the wake.

Generally they encourage reattachment. What is your test vehicle? For the example shown, I'd attack the vortexes coming off the A-pillar and maybe address the front wheels on the lower doors.

Do you have an algorithm for sizing the power supply, generator and actuator area?

Why not make the whole surface of the car plasma. :)


The test vehicle is an audi a3 p8a chassis.

No idea yet on how to size the power supply.

I was thinking of making strips and as long as the supply can handle and then continuing with another supply and strip.

Same as with golf ball dimples, they have no effect in most areas. With a golf ball it's at ~115° to the direction of flight.

If I had the time I'd dredge up a link to using serpentine strips.

Tuft testing?

Plasma is such a drag.


Ayaks
https://en.wikipedia.org/wiki/Ayaks
https://upload.wikimedia.org/wikiped...75px-Ayaks.jpg
Magnetohydrodynamics?

Feng sui is indistinguishable from fluid dynamics.

teoman — Don't forget to post about any results. I've identified an opportunity myself. I'm holding a low reservation number for one of these:
https://ecomodder.com/forum/member-f...8-124-1186.jpg
I want to substitute a steel VW wheel for the two fronts so that I can used Moon disks. Then I want to bend a circular strip of dielectric material into a conic section and attach it to the outer rear edge of the front fender. With a thick copper wire bent into a serpentine on the outside leading edge and the other behind the trailing edge.

Best case it would blow a sheet of air against the main body, to re-attach the turbulence coming from the A-arm suspension.

It's an electric vehicle, so power supply is no problem.

The power supply will promise to be annoying and inefficient. I do have concerns about plasma and the general public being in close proximity.

I looked at that website and understand the concept, but is it really plasma? Seemed to be ionized air, which doesn't fit the definition of plasma. I'd expect ionizing air to be less energy intensive as creating plasma.

The gating factor would be whether the aero improvement would pay for itself and not reduce range.

It would be inefficient to switch it on below 25mph. Above 25mph there would be other concerns. :)

edit: No true plasma fallacy ;)
A gas of plasma is poor wording.

Speaking of plasma:
https://www.youtube.com/watch?v=xa8EeTa2x7c
OEM parts FTW. One electrode is buried behind the dielectric. I doubt touching it would do anything. Maybe inhale a little ozone?

Anyway 50Kvolts would be enough to experiment with active aerodynamics.

Electrostatic precipitation
 

If you are driving a car with high voltage on it near a dusty diesel fume polluted road surface aren't you essentially making an electrostatic precipitator? https://en.wikipedia.org/wiki/Electr...c_precipitator

Surely your car then becomes a near literal dust magnet attracting all the carcinogenic soot particles from nearby cars.

plasma
 

Again, this is ballistic flow, not germane to road vehicles.
For it to be magnetohydrodynamics, we'd be introducing an electric potential, to accelerate the air itself to create jet thrust. I can't imagine that the mechanical efficiency could exceed that of an electric traction motor. It's a second law of thermodynamics fail.:(