# Maximizing Lift Through Vortex Generation on Airplanes

• Puglife
In summary, the wingtip vortices on a delta wing are formed due to boundary layer separation, and they increase lift and decrease drag. They are directed over the wing by a vortex generator on the leading edge.
Puglife
For an airplane, their are multiple types of lift, camber, angle of attack, pressure difference, and vortex lift.

I understand that at the end of wings the low pressure at the top, and high pressure on the bottom causes their to be a vortex formed. My question is, how exactly do they use that vortex for lift?

I believe that they have wings with extremely high aspect ratios, so that the entire wing can be treated as a wing tip (or atleast I think so). so how do they use that vortex for lift?

Thank You, your help is much appreciated.

Drakkith
Puglife said:
For an airplane, their are multiple types of lift, camber, angle of attack, pressure difference, and vortex lift.
It is really better to say that there is only one type of lift, and it is from pressure difference. The causes of pressure difference can include camber and angle of attack. Vortices are an indicator of pressure differences and go hand-in-hand with it. It is true that the speed of air in a vortex makes it less effective in increasing the pressure on top.

I understand that at the end of wings the low pressure at the top, and high pressure on the bottom causes their to be a vortex formed. My question is, how exactly do they use that vortex for lift?
If there is low pressure at the top and high pressure at the bottom, then there is lift. The vortex just goes hand-in-hand with that pressure difference. Air gets drawn in by the pressure difference and forms a vortex, so it is just an indicator of the pressure difference.

I believe that they have wings with extremely high aspect ratios, so that the entire wing can be treated as a wing tip (or atleast I think so). so how do they use that vortex for lift?
It is really the opposite. A very high aspect ratio means that the wing tips are a small part of the equation. So the higher the aspect ratio, the less the wing can be treated as a wing tip.

Ok, so how do they get lift from the vortexs that form?

Wingtip vortices are actually usually harmful to wings, not beneficial. This is why you see winglets and other wingtip devices on most planes these days.

At any rate, the wing doesn't just "get lift from the vortices." The vortices are one part of a more complex flow field that, as a whole, determines the lift on a wing. Subsonic air flow, in general, is not linear and is not a situation where superposition holds without certain simplifying assumptions. If you simply remove the vortices from the picture, you've fundamentally altered the flow field and it doesn't work.

Wingtip vortices are actually usually harmful to wings, not beneficial. This is why you see winglets and other wingtip devices on most planes these days.

At any rate, the wing doesn't just "get lift from the vortices." The vortices are one part of a more complex flow field that, as a whole, determines the lift on a wing. Subsonic air flow, in general, is not linear and is not a situation where superposition holds without certain simplifying assumptions. If you simply remove the vortices from the picture, you've fundamentally altered the flow field and it doesn't work.
Delta wings use the votexs, and direct them over the wing, to create a low pressure system. What I am wondering is how it is directed over the wing?

You are talking about the leading edge vortex that forms on delta wings? That's a different story. That is unrelated to the wingtip vortices you cited in your original post. The vortices at the leading edge of a delta wing form due to boundary-layer separation at the leading edge and they get "trapped" there by the air flowing over the top of them and reattaching to the wing behind them. They increase lift essentially because they accelerate the air more than the wing otherwise would and therefore lower the pressure in that region. They also increase drag fairly substantially, which is why delta wings are inefficient at low speeds.

You are talking about the leading edge vortex that forms on delta wings? That's a different story. That is unrelated to the wingtip vortices you cited in your original post. The vortices at the leading edge of a delta wing form due to boundary-layer separation at the leading edge and they get "trapped" there by the air flowing over the top of them and reattaching to the wing behind them. They increase lift essentially because they accelerate the air more than the wing otherwise would and therefore lower the pressure in that region. They also increase drag fairly substantially, which is why delta wings are inefficient at low speeds.
So how is it that the leading edge vortex stocks to the top of the wing?

Thank you all, you all are super helpful

Like I said, it originates there as a result of leading edge boundary-layer separation and stays there because the air traveling over the top of it essentially wraps back around and reattached to the wing behind it. It's kind of like it is held there in a little pocket.

This is a neat website I discovered years ago about vortex lift. It provides a cool introduction into the subject and some nice figures too.

http://www.acsol.net/~nmasters/vortex-lift/

Last edited by a moderator:
If I recall correctly, for a delta wing, the leading edge vortices flow somewhat outwards along the leading edge as well as backwards across the wing. The AOA of attack for stall on a delta wing is around 20º, much greater than a conventional wing.

Like I said, it originates there as a result of leading edge boundary-layer separation and stays there because the air traveling over the top of it essentially wraps back around and reattached to the wing behind it. It's kind of like it is held there in a little pocket.
Thank you, Thank you all Very much for all of your help

## 1. How does vortex generation help maximize lift on airplanes?

Vortex generation is a technique used to create vortices, or rotating air currents, on the wings of an airplane. These vortices help to energize the boundary layer of air flowing over the wings, creating more lift and reducing drag. This results in increased efficiency and lift for the airplane.

## 2. What are the different methods of generating vortices on airplanes?

There are several methods for generating vortices on airplanes, including the use of wingtip devices such as winglets or raked wingtips, as well as the use of vortex generators (small devices placed on the wing surface to create vortices).

## 3. How do engineers determine the optimal placement and design of vortex generators for a specific airplane?

Engineers use computational fluid dynamics (CFD) simulations and wind tunnel testing to determine the ideal placement and design of vortex generators for a particular airplane. Factors such as wing shape, airfoil profile, and flight conditions are taken into consideration to maximize the effectiveness of vortex generation.

## 4. Can vortex generation be used on all types of airplanes?

Vortex generation can be used on a wide range of airplanes, from small single-engine planes to large commercial airliners. However, the specific design and placement of vortex generators may vary depending on the size and purpose of the airplane.

## 5. Are there any potential drawbacks to using vortex generation on airplanes?

One potential drawback of vortex generation is the added weight and complexity it may add to the airplane's design. Additionally, if not designed and placed correctly, vortex generators may actually increase drag and decrease efficiency. Therefore, careful consideration and testing must be done to ensure the benefits of vortex generation outweigh any potential drawbacks.

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