(Source: www.airliners.net)
These circles I believe are the wing tip vortex formed by the propeller tips or is it just due to the rotation of the propeller. How does this occur?
$\begingroup$
$\endgroup$
5
-
15$\begingroup$ Ethan. Do yourself a favour. Many people, in many of your questions have pointed out that wings, propellor blades and rotor blades are all the same thing. If you would finally pay attention to this, and learn it, then you would have realised and known that these are tip vortices just like wing tip vortices. The problem is, if you keep asking the same questions and not learning from people trying to help, the help will dry up. $\endgroup$– SimonOct 5, 2015 at 14:21
-
1$\begingroup$ @Simon in my head I pictured the wake on a blade to be different and that confused me to the point of I didnt know what the circles where for. $\endgroup$– EthanOct 5, 2015 at 18:43
-
2$\begingroup$ NP. So hopefully, you now get the point that wings, propellor blades and rotor blades are all the same thing. An aerofoil that accelerates air to produce a force. Different purposes, different shapes, different designs, but all the same thing. $\endgroup$– SimonOct 5, 2015 at 18:49
-
1$\begingroup$ @Simon I do have a good understanding of it now $\endgroup$– EthanOct 5, 2015 at 18:52
-
$\begingroup$ I've seen that exact picture posted on another question (or possibly answer) somewhere, but can't find it at the moment. This is easily a duplicate of that question, if not 1/2 a dozen others. $\endgroup$– FreeManOct 5, 2015 at 19:38
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
5
They are tip vortices formed by the propeller, just like the wing tip vortices.
The propeller produces thrust, just like the normal wing produces lift. As any wing of finite length produces vortices, the propeller also produces them and that is what you see in the picture.
This is not only limited to propellers. The helicopter rotors also do the same thing.
answered Oct 5, 2015 at 12:02
-
$\begingroup$ can these viewed at particular environment like humidity, moisture, fog etc? or special camera needs to be used to capture these vortices, as these are created by all type of propellers in aircraft as well in helicopters. $\endgroup$– LuckyOct 5, 2015 at 13:04
-
1$\begingroup$ @Lucky These require no special cameras. These vortices are always formed by the propeller/aircraft but usually become visible in humid conditions. $\endgroup$ Oct 5, 2015 at 13:11
-
2$\begingroup$ @Lucky When air is pressurised, it's ability to hold moisture as a vapour reduces and the water condenses out. In completely dry air, you would never see them. You would need smoke, dust or some other particulate suspended in the air to see them but when the conditions are right (temperate, humidity and dew point), then water in the air condenses out when under pressure. $\endgroup$– SimonOct 5, 2015 at 14:20
-
$\begingroup$ @aeroalias No special cameras, but a phone won't do in most circumstances. You'll need to be able to control shutter speed and aperture in order to capture just enough rotations for getting a pretty picture. $\endgroup$ Oct 5, 2015 at 20:56
-
$\begingroup$ Why are these vortices? Vortices are produced by anything in the air that moves pretty much. What you can see on the picture however is actually water vapor or contrails. $\endgroup$– AlexusOct 5, 2015 at 23:58
$\begingroup$
$\endgroup$
The pressure in the core of a vortex (such as that shed at the tip of an operating propeller, rotor, wing or extended flap) is reduced well below ambient pressure. The temperature is also lower than ambient because of the lowered pressure. If the temperature is lowered to the dew point, the water vapour will condense and become visible revealing the vortex core.
This is aerodynamic condensation. It is related to the over-wing condensation sometimes seen during landings and takeoffs in very humid conditions, and around the wings in extreme aerobatic manoeuvres. It is caused by the lowering of pressure and the accompanying lowering of temperature.
