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Does wing produce higher lift with VGs even at low AoAs(let say 10°) compare with wing without VGs?

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First of all, for a straight wing with a cambered airfoil, 10° is not a low angle of attack anymore.

At all flight speeds vortex generators intensify the mixing of high-energy outer air with the slowed-down air of the boundary layer, thickening the boundary layer in the process while keeping flow speed at the surface up. This helps to delay flow separation (which is defined as airflow at the surface coming to a standstill from the deceleration caused by an adverse pressure gradient).

In poorly designed wings those vortex generators also help with control surface linearity and effectivity. A good example for the clever application of vortex generators is the horizontal tail of the Short Belfast, where the vortex generators hide in the elevator hinge gap at small deflections but will protrude into the airflow once the elevator is moved to larger negative deflections, helping to increase the linear range of the elevator (independent of angle of attack).

Horizontal tail of a Short Belfast

Horizontal tail of a Short Belfast (own work)

Low Speed

Friction is proportional to the speed gradient at the surface. Keeping this surface speed up will obviously increase friction drag. However, it will also help to shift flow separation to higher angles of attack, so the linear part of the lift curve slope will reach to higher angles of attack. This reduces the minimum flight speed by allowing attached flow at slightly higher angles of attack compared to a wing without vortex generators. But that will only make a difference in lift close to stall and not at lower angles of attack. Drag, however, will be higher over the whole angle of attack range.

High Speed

Vortex generators on the outer wing of a Boeing 737, for example, help to fix the location of the shock by preventing flow separation past the shock. Without the vortex generators, the shock location and intensity would fluctuate and with it lift, leading to an effect called "buzz", resulting from the high-frequency lift variation.

Vortex generators on the outer wing of a Boeing 737-800

Vortex generators on the outer wing of a Boeing 737-800 (picture source)

This happens already at low angles of attack (typically 3° to 5°) and does indeed increase lift in the low-lift part of the cycle of lift variation. This effect is small, but by eliminating the cyclic loading makes a big difference in flight comfort and the wing's fatigue life.

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  • $\begingroup$ Can I increase lift at straight wing with big vortex/strakes/generators that produce big strong vortexes, so all upper surface will be coverd with big swirling flow/"tornados"? Big mean,much bigger than boundary layer height, just like fighter jet has vortex from strakes.. I am talking for AoAs where flow is still attached to surface, so basically I am comparing laminar flow vs big vortex flow over upper surface of wing.I know this will produce huge drag, but I am now just interested for lift. $\endgroup$
    – user707264
    Apr 13, 2023 at 9:47
  • $\begingroup$ @user207141 This would be a hugely inefficient way of getting extra lift. Better to add a flap, ideally with a gap and some chord increase on deflection. This can be folded away for cruise while the VGs will be exposed all the time. $\endgroup$ Apr 13, 2023 at 10:32
  • $\begingroup$ high lift with tons of drag. Joseph Katz work a lot on that. pages 47-50 viterbik12.usc.edu/wp-content/uploads/2019/06/… $\endgroup$
    – user707264
    Apr 13, 2023 at 11:03
  • $\begingroup$ @user207141 the vortex generators on race car underbodies are more like diffusors than simple aviation-type vortex generators. $\endgroup$ Apr 13, 2023 at 15:46
  • $\begingroup$ Why like diffusors? Isnt they more like strakes at fighter jets which deliberately produce strong vortex flow? imgr1.auto-motor-und-sport.de/… $\endgroup$
    – user707264
    Apr 13, 2023 at 18:23
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I believe they do if the vortex generators are big enough. The most extreme case of this is the vortex lift on a delta wing at high angles of attack, like the concorde. this article https://ntrs.nasa.gov/api/citations/19930087240/downloads/19930087240.pdf provides some experimental data

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