Plasma drag reduction

[freebeard]

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]

[kach22i]

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

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]

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

[freebeard]

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

[kach22i]

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]

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

[aerohead]

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.

[freebeard]

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;

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]

Originally Posted by freebeard

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.