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-   -   Plasma drag reduction (https://ecomodder.com/forum/showthread.php/plasma-drag-reduction-33671.html)

redneck 04-09-2016 12:08 AM

Plasma drag reduction
 
.

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

Quote:

Our patented technology (s) uses an active flow control system utilizing plasma actuators has been developed at the University of Notre Dame. This system is capable of generating a body force which controls flow separation from a vehicle. By controlling flow separation, the drag force on a vehicle is minimized. In essence, a vehicle can be streamlined independent of its actual shape. Physical devices such as spoilers, bobtails, flow plates, and diverter tabs have been used to move the airflow in a desired direction. Plasma actuators ionize the local airflow to induce a similar affect without the added structural components or weight. Even the best designed physical devices attempt to divert flow, unlike plasmas which modify the existing flow field.
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:


>

MobilOne 04-09-2016 12:45 AM

back to the future

freebeard 04-09-2016 03:42 AM

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.

sendler 04-09-2016 09:17 AM

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?

freebeard 04-09-2016 01:34 PM

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.

PranayBajjuri 04-09-2016 10:38 PM

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

redneck 04-09-2016 10:52 PM

.

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...???


>

PranayBajjuri 04-09-2016 11:17 PM

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

freebeard 08-27-2016 04:34 AM

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

Are things on track?

Stubby79 08-27-2016 09:32 AM

Deflector shield on full; engage warp drive?

freebeard 03-30-2017 04:21 AM

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.

BamZipPow 03-30-2017 10:37 PM

https://3c1703fe8d.site.internapcdn....signcoulds.jpg

kach22i 03-31-2017 08:47 AM

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
Quote:

Published on Mar 28, 2017

For road vehicles, wind resistance increases fuel consumption. But one way to fight wind is with wind. Researchers in Sweden are experimenting with reducing drag on trucks with electric wind devices that mimic the way vortex generators increase lift on airplane wings.

Stubby79 03-31-2017 12:19 PM

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

freebeard 03-31-2017 01:48 PM

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

kach22i 03-31-2017 03:15 PM

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.

ASV 04-02-2017 04:46 PM

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

aerohead 04-08-2017 01:45 PM

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.
--------------------------------------------------------------------------
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.
--------------------------------------------------------------------------
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.

freebeard 04-08-2017 02:45 PM

Quote:

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.
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;

Quote:

Upward Bound: Mass Drivers
Isaac Arthur
2 days ago 31,178 views
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.

aerohead 04-08-2017 04:35 PM

virtual air tabs
 
Quote:

Originally Posted by freebeard (Post 538000)
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.

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.

freebeard 04-08-2017 08:27 PM

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

Quote:

The example, from an Airbus A380, combines a pitot tube (right) with a static port and an angle-of-attack vane (left). Air-flow is right to left.
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?

ChazInMT 04-10-2017 04:55 AM

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?

freebeard 04-10-2017 01:40 PM

2nd paragraph is unnecessary.

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

aerohead 04-15-2017 01:43 PM

concept
 
Quote:

Originally Posted by ChazInMT (Post 538150)
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?

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.

freebeard 05-19-2017 03:27 PM

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:
Quote:

<meta property="og:description" content="Jet engines that compress gas into a plasma have been successfully tested at ground level for the first time">
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:

freebeard 05-21-2017 09:39 PM

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

https://arxiv.org/abs/1609.04054
Quote:

A new breakthrough in jet propulsion technology since the invention of the jet engine is achieved. The first critical tests for future air-breathing magneto-plasma propulsion systems have been successfully completed... Such a new pulsed plasma propulsion system driven with one thousand pulses per second would already have thrust-to-area ratios (50-150 kN/m2) of modern jet engines.
First problem seems to be it's deafening. :eek:

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

teoman 09-30-2019 04:18 PM

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?

freebeard 09-30-2019 04:37 PM

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?

teoman 09-30-2019 04:48 PM

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.

freebeard 09-30-2019 05:26 PM

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.

teoman 09-30-2019 08:18 PM

Tuft testing?

kach22i 10-03-2019 10:04 AM

Plasma is such a drag.


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

Plasma sheath

As altitude increases, the electrical resistance of air decreases according to Paschen's law. The air at the nose of Ayaks is ionized. Besides e-beams and HF pulse discharges, a high voltage is produced by the Hall effect in the MHD generator that allows a planar glow discharge to be emitted from the sharp nose of the aircraft and the thin leading edges of its wings, by a St. Elmo's fire effect. Such a plasma cushion in front and around the aircraft offers several advantages:[35][36][2]

The ionized air becomes electrically conductive, which allows the MHD generator to work and decelerate the flow down to the air-breathing jet engines.

The MHD-controlled inlet ramp allows to vector the flow as a shock-on-lip without physical inlet cones.

Electric charges mixed with the fuel increase the combustion effectiveness.

The bow shock wave is detached further ahead of the aircraft, the energy deposition in this region acting as a virtual blunted nose, although the nose stays physically very sharp. This minimizes the heat flux on materials.[35]

The temperature gradient in the air is locally modified, hence the speed of sound value, which mitigates and softens the shock wave. This lowers thermal effects on materials further, as well as the wave drag.[37][38][35]

The plasma cocoon surrounding the whole aircraft gives plasma stealth. Combined with hypersonic speeds and maneuverability, such a platform would be very difficult to detect, track and target
.
Magnetohydrodynamics?

Piotrsko 10-04-2019 12:41 PM

Feng sui is indistinguishable from fluid dynamics.

freebeard 10-08-2019 01:54 AM

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.

Piotrsko 10-08-2019 11:30 AM

Quote:

Originally Posted by freebeard (Post 608692)

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.

redpoint5 10-08-2019 01:33 PM

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.

freebeard 10-08-2019 01:56 PM

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 ;)
Quote:

Originally Posted by Wikipedia
Plasma - physics
Plasma is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s. It consists of a gas of ions, atoms which have some of their orbital electrons removed, and free electrons.

A gas of plasma is poor wording.


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