Plasma drag reduction

[freebeard]

https://en.wikipedia.org/wiki/Pitot_tube

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]

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]

2nd paragraph is unnecessary.

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

[aerohead]

Originally Posted by ChazInMT

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.

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]

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:

<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://www.google.com/search?q=plas...6SD-UJRtJ_bkM:

[freebeard]

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

https://arxiv.org/abs/1609.04054

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.

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

[teoman]

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?




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

[freebeard]

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]

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]

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.