MHD {Magneto-Hydro-Dynamique} and research by Jean-Pierre Petit

[Christophe]

Maieuuh I explained, I said "ionic engine"!

I thought it was clear enough!

What are the differences with MHD?

[izentrop]

Between the "classical" fluid mechanics and the magnetohydrodynamics, there is the electrohydrodynamics or mechanics of fluids ionized in the presence of electric fields (electrostatic), but without magnetic field. https://fr.wikipedia.org/wiki/Magn%C3%A ... odynamique

I do not know what to think because electricity without magnetism is not possible.
You're right, the difference is not obvious https://fr.wikipedia.org/wiki/Acc%C3%A9 ... n_spatiale

The energy that propelled the aircraft from the video was not stupendous, of the order of 80 joules, we are not yet at crazy powers.

[Christophe]

Yes I remember that there was a magnetic component in the MHD, only here, as you say, any moving electron creates a magnetic field ... so not obvious, actually ...

When I asked for difference, it was, also, especially, at the performance level.

The energy that propelled the aircraft from the video was not stupendous, of the order of 80 joules, we are not yet at crazy powers.

With what return? Because that's what counts ... more than power (after it's just a story of scale ...)

2 years ago I put a calculation MHD to propel an electric paramotor: it needed a gigantic power to get 500 N of push ... I think it was, from memory, more than 50 kW ... ( to check)

50 kW with a conventional propeller this gives about 2500 N with a propulsive efficiency of 70-80% (table corner calculation)

One of the articles talks about 50% propulsive efficiency for the ion engine, which would be an extraordinary advance compared to the MHD (15% yield based on these figures)!

[Exnihiloest]

Yes I remember that there was a magnetic component in the MHD, only here, as you say, every moving electron creates a magnetic field ...

Only in the repository of the observer. I specify, otherwise people will believe that a second electron moving in concert with the first would suffer the magnetic field of the other, which would be as wrong as to think that tomorrow, the liter of unleaded will go back under the bar of the euro.

[izentrop]

as you say, every moving electron creates a magnetic field ... so not flagrant, actually ...

In fact it is normal because there is no electric current but a flow of ion mainly nitrogen from the air. A potential difference of 40 kV between a fine wire and a fin causes the ionic wind that moves the aircraft.
Explanation here: https://www.nature.com/articles/d41586-018-07477-9

the yield of 50% is under condition:

if the speed reaches 300 ms -1, 2 efficiency, 6 can reach 50%. Second, many studies have shown that ionic wind can improve the aerodynamics of 7 aircraft wings. Thirdly, this technique could facilitate what is known as 8 distributed propulsion, considered as a major axis for improving aviation. https://www.nature.com/articles/d41586-018-07411-z

[SixK]

I dig up this subject for the 2nd time.
An interview with Jean-Pierre Petit on Tinkerview.

it's dated, but rather interesting.

[Christophe]

Not bad the little trick to print Young's slits https://fr.wikipedia.org/wiki/Fentes_de_Young for mobile phone!

I will print one ... if I find the model!

[Christophe]

Not found on https://www.thingiverse.com/search?q=Young+mobile

If someone provides me with the dimensions I would like to model one

[Christophe]

We have in this passage the proof that all geniuses are autistic ... at least partially:

What ? What ? What ?

[Christophe]

I listened to everything JP Petit ... I understood things and I didn't understand things ... I think it's normal!

But I liked his conclusion as a "scholar"