0
$\begingroup$

What I'm asking is does all of the air that spills from the high pressure bottom of the wingtip get pulled by the low pressure top of the wing? So some of the air curls around the wingtip to make a vortex, but does that mean all of the air gets pulled by the top of the wing and make a vortex? Does some air escape past the low pressure top of the wing and not make a vortex at all?

Thanks!

Improve this question
$\endgroup$

2 Answers 2

Reset to default
1
$\begingroup$

To address this question, let's review the aerodynamics involved in aircraft wingtips and the formation of wingtip vortices.

Lift generation

A wing generates lift by creating a pressure difference between its upper and lower surfaces. The air pressure is higher under the wing and lower above it.

This pressure difference is the main principle of lift generation.

Wingtip Vortex

The high-pressure air from beneath the wing tends to flow towards the low-pressure area above the wing, this happens along the entire wing, but especially at the wingtips. This is because the wing abruptly ends, in an infinite wing, wingtip vortices would not generate.

This image gives a good overview:

enter image description here

These vortices are a byproduct of the lift generated by the wing and are strongest when the wing generates the most lift, such as during takeoff and landing.

Is all the airflow turning into vortices?

Long story short

The fluid flow dynamics involved in lift generation are complex and subject to many variables. Not all the air will be neatly channeled into the vortices.

While a significant portion of the air contributes to forming these vortices, it's not necessarily true that all of it does. Some airflow may pass around the wingtip without being involved in the vortex creation.

Many variables can alter the actual path of the air; these factors can include:

  1. Dirt or Debris on the Wing: Accumulating dirt, ice, or other debris on the wing can alter the airflow. These contaminants can disrupt the smooth flow of air, potentially affecting lift and drag characteristics. This disruption can also modify the formation and strength of wingtip vortices.

  2. Accessories like Winglets: Winglets, which are vertical extensions at the wingtips, are designed to reduce the strength of wingtip vortices by redirecting the airflow to diminish the intensity of these vortices. They also improve the overall aerodynamic efficiency of the wing.

  3. Wing Design and Shape: Different wing designs, shapes, and sizes will influence how air flows around them, including how vortices form at the wingtips. Factors like aspect ratio, wing sweep, and camber affect aerodynamic performance.

  4. Speed and Angle of Attack: The aircraft's speed and angle of attack significantly influence airflow patterns. At higher angles of attack, which occur during takeoff and landing, wingtip vortices are typically stronger.

Improve this answer
$\endgroup$
4
  • $\begingroup$ hmm okay. My thinking is that the air that the wing is approaching hits the bottom, creating a high pressure there. Then, the air on the upper surface of the wing is becoming lower pressure because the wings surface is blocking the airflow. (To make it easier to understand, imagine the wing at a really high AoA) So after that, the flow leaking from the bottom of the wing would have to all get pulled by the upper surface because the 2 surfaces would have equal and opposite pressure differences. Not to mention the effect of the airfoil curve making the upper surface even lower pressure. $\endgroup$
    – Wyatt
    Commented Dec 6, 2023 at 21:16
  • $\begingroup$ @Wyatt Thinking of airflow hitting the airfoil like bullets striking a plate is a useful intuition only beyond Mach 5 or so. When subsonic, better than worrying "why does the air do this," just note "it has been observed that the air flows like this near this airfoil under these conditions." Pulling, leaking, pushing, all eventually lead to fallacies. $\endgroup$
    – Camille Goudeseune
    Commented Dec 28, 2023 at 2:45
  • $\begingroup$ @CamilleGoudeseune oh okay, then what would prove my thought process wrong there? Like why is it only useful above Mach 5? $\endgroup$
    – Wyatt
    Commented Dec 28, 2023 at 3:19
  • 1
    $\begingroup$ @Wyatt above Mach 5, see aviation.stackexchange.com/a/96788/31425 and the other answers there showing how simple things are when hypersonic. When subsonic, I've found it more useful (not more right, just more useful) to think only of air flowing from high to low pressure, and not going on to call the parts of the flow things like pulling or leaking or whatever. $\endgroup$
    – Camille Goudeseune
    Commented Dec 28, 2023 at 17:11
0
$\begingroup$

I will answer from the understanding of question I have,

  1. Firstly, to the question "the air that spills from the high pressure bottom of the wingtip get pulled by the low pressure top of the wing?", I don't think all air that spills form low pressure region reach the top surface since the concept of air as particle can lead it to move it in any path once spilled rather than forming the vortex.

  2. To "Does some air escape past the low pressure top of the wing and not make a vortex at all?" I think yes since there is no mechanism to my understanding that will prevent this.

Improve this answer
$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .