What does mean for this gas when aircraft takeoff and landing?


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If it was cold it might be deicer or it could be water moisture like dew drops

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I think I’ve seen this phenomenon before. It has to do with the engines and the moisture I’m pretty sure

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My best guess is that these are leading edge slat, lift condensation vortices.

Wing tip vortices (rotating mini tornadoes of turbulent air) occur because at the edges of the lift producing areas, the pressure differential between upper and lower surface of the wing has to meet.

And the spilling of this pressure difference together forces the rotation to start.

You’ll notice the leading edge slats have their own “mini wing” tips where there is a similar pressure difference spill over.

The visible condensation occurs when the air has sufficient humidity that the dropped pressure in the center of the vortex is below the dew point.

So this looks like the conditions for condensation were right at the inboard leading edge slat’s edge.

There are spinning vortices coming off all lift generating edges. But conditions aren’t usually ripe for condensation to make them visible.

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Can they be formed from left over deicer?

I wouldn’t think so. But check out this cool video of this going from nothing to immediate condensation vortices after the wheels leave the ground. Watch starting around 1:45

Condensation and Vortices - Visible wake turbulence VORTEX - YouTube

It’s exactly in the same place - at the inner leading edge slat’s edge.

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I happened to be on a flight yesterday, I think it’s just the way the air moves over the wing

As the angle of attack increases, the airflow accelerates over the leading edge of the wing. This accelerated air has a lower pressure than the surrounding air which leads to condensation when the conditions allow. The curvature of the wing acts as a Venturi as described in Bernoulli’s Principle. As a fluids velocity increases, its internal pressure decreases. Same reason how lift is achieved I believe. A similar phenomenon occurs in the intakes of jet engines, the rapid intake of air at high thrust settings is furthered by a rapid decrease in surrounding air pressure.

@adit is correct the first time. Simply just vortice caused by pressures curling over an edge

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This is good but not the whole picture :)

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And this vortice you pictured is probably from a VG installed on the inboard side of the engine cowl… but a jet driver like deer would probably know better than me on that one lol 🤪

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Condensation can certainly occur across the entire wing, if conditions are right:

In the OP’s photo however, the pressure drop induced condensation appears to be limited to the one location. And in this case it is definetely the spill over spinning vortices.

image

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That first shot is so insane

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That’s what I thought when I first saw it. And it appears to have the whole package - with some condensation vortices off the flap edges as well.

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I have to admit it’s been awhile since I’ve studied, I’m getting ready to start flight training again. Still have the training wheels on haha, but I tried to be basic with my response 🤙🏻

Hey Muktharr, I found a nice video on YT starting on timestamp 2:20 where you can see the engine cowling strake from a nice angle. Hope you like it!😉
Those fins or votex generators are placed to improve the airflow over the wing during critical
flight phases due to the position of the engine itself and abscence of the slats on that part of the wing. In general, when air pressure drops (during turbulence) temperature drops and the air reaches its dewpoint followed by condensation. (Especially when humidity is high)

Cheers Stef

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image

It’s the same as this, but WAY WAY less forceful.

What aircraft model is that? I’m curious to see what it has in the way of cowling vortex generator.

It appears so.

Awesome video. I’m also trying to understand in the earlier part, the intake vortex. I don’t get right away why it looks like that. Somehow that effect gets transferred forward of the turbine.

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Hey @adit, sorry for the late reply.
How strange it sounds, just before the compressor or fan on bigger engines (i.e. the intake of the engine) there is still an air expansion. This in combination with the acceleration of the air when the engine accelerates (like in the video) “Bernoulli” looks around the corner.😉
Total pressure= dynamic pressure + static pressure remains constant. Airflow increases and static pressure drops which results in temperature drop> air reaches dewpoint> condensation