vitekps

Yo! this is next, hard riddle from this Polish teenager;P
So what i want to know is: what is this "mini tornado" (if i can say like that) under the engine becouse i sow it and it's awesome! hehe I suppose that it is connected with circle build of construction of the engine.
sorry for my eng;P and becouse of propably confused reason use semple language plz

vitekps

[IMG]file:///C:/Users/Vitold/AppData/Local/Temp/moz-screenshot.png[/IMG][IMG]file:///C:/Users/Vitold/AppData/Local/Temp/moz-screenshot-1.png[/IMG][IMG]file:///C:/Users/Vitold/AppData/Local/Temp/moz-screenshot-2.png[/IMG][IMG]file:///C:/Users/Vitold/AppData/Local/Temp/moz-screenshot-3.png[/IMG]

usmc-sgt

Huh?

jcaplins

I'll use that "huh?" as a "bump".

Hello, I am a polish teenager with a question.
I would like to know: what is the "mini-tornado" (if I can say it like that?) under the engine? I saw it and i thought it was awesome! {he he} I suppose it has something to do with the rotational construction and forces of the engine.
Sorry for the English, It is probably confusing. please use simple terms when responding.



You are correct. It has to do with the air being pulled into the engine by the rotating blades in the engine. I'll let a jet person actually answer the question with more depth.

jungle

The engine fan creates a vortex because of the lower pressure at the face of the fan and higher pressure on the ground. The differential in pressure is also what forms a small vortex in a sink drain.
The vortex becomes visible when high humidity, rain or snow are present,but it is always there. The intake danger zone extends all around the engine in a hemisphere and may extend for several feet. At high power settings it can easily pull a human into the engine. Intake velocity can exceed 140 knots even at idle.


In the photo the water vapor is made visible by the pressure differential, lowering the pressure causes the vapor to condense.


http://www.youtube.com/watch?v=5jxcSY1AwrM

Dubes

YouTube - Boeing 777-200ER from Various Airlines at Ringway/Manchester Intl Airport by Simon Lowe

HSLD

Wentylator silnika tworzy wir ze względu na niższe ciśnienie w obliczu wentylatora oraz wyższe ciśnienie w terenie. Różnicy ciśnienia jest także to, co tworzy mały wir w drenażu zlewu.

Vortex staje się widoczne, gdy wysoka wilgotność, deszcz czy śnieg są obecne, ale zawsze istnieje. Strefie niebezpiecznej dawki obejmuje całego silnika w półkulę i może trwać kilka metrów. Przy wysokich ustawienia mocy można go łatwo wyciągnąć człowieka w silniku. Spożycie może przekroczyć prędkość 140 węzłów nawet na biegu jałowym.

vitekps

Wow
Guyes, U are incredible;*
thx!

Cubdriver

This is a prime example of Helmholtz's Vortex Theorems. The first two theorems are:

Helmholtz’s first theorem:
The strength of a vortex filament is constant along its length.

Helmholtz’s second theorem:
A vortex filament cannot end in a fluid; it must extend to the boundaries of the fluid or form a closed path.

In other words, once a vortex forms it cannot just wind into the air and stop, it must meet itself on the other end, or in this case meet the ground (literally) where the reflected opposites are found.

Another common example of this is found in the behavior of wingtip vortices. They do not dissipate at all, except by the means of viscous friction, because in the non-viscous case (meaning for a perfectly thin fluid) they cannot dissipate. They MUST meet themselves where they formed to reach mathematical singularity. The wingtip vortices will try for as long as they exist unencumbered by frictional dissipation to meet themselves back at the two points on the runway where they first formed. In other words, if friction did not dissipate wingtip vortices and you could see them using smoke or fog, they would extend as many miles as required to meet themselves back where they formed. This is the Second Theorem: they must form a closed path.

We had a heated discussion at APC some months ago lift in ground effect. I argued that lift in ground effect is theoretically diminished, and I was technically correct. However, I think I lost the argument because common experience in flying airplanes is that most airplanes will tend to float in ground effect and no one was convinced. In this example, however, you can clearly see theory meeting experience.