Squeezing in the bernoulli's effect wherever can be makes good sense (short of making it a flying wing design) but during fast high AoA manoeuvres wouldn't the generated vortices be more pronounced and hence at least somewhat clearly visible passing over the canopy? Like they are over the wings when generated from the LERX? I've tried finding evidence of it but to no avail,
Hi
@krash
Yes indeed bernoulli's effect is what generates the pressure differential across the top and bottom surface of the "finite wing".It is this pressure differential again that pushes the circulation of air from higher pressure at bottom to low pressure at top giving rise to "vortices". I mean in a continuous flow along the chord of the wing,if you take two points 1 and 2,top and bottom of the wing respectively and apply the bernoulli(which is essentially a conservation principle)-
P1+0.5*rho*v1^2+rho*g*h=P2+0.5*rho*v2^2+rho*g*h.
this can be re-written as P2-P1=0.5*rho(v1^2-v2^2)=delta(P)----------------1
Eqn 1 is very crucial and relates the difference in velocity to difference in pressure.Now the velocity of air moving over the wing is higher than the air moving below it because of the camber- the air over it has to travel longer distance in same amount of time! So by increasing the camber you also increase the pressure differential.
But how do you increase the camber?- by control surfaces!
We also know that water boils at a lesser temperature if the surface pressure is low.Now if by some means you can bring down the pressure over the wings,you can boil water(from atmosphere) at normal ambient temperature! THats what essential happens when you see that white smoke trail from the LERX in f-16!
In picture above,i.e F-16 with large LERX,you can clearly see a very strong vortex over the wing- itz effect is similar to lets say the compound delta you find in LCA!- in both these cases,these wing portions help in pushing flight envelop by increasing Clmax- or the max allowable AoA before the wing stalls!
In case of LCA though,in sub-sonic regime as we increase the AoA,the comound delta structure- double angle at the leading edge section of the wing- helps in creating vortex in a much controlled fashion thereby reducing the total drag!
The stronger vortex generation you can render,more will be your evaporation. The strakes on the other hand are not big enough to create such strong vortices- although a group of small strakes can generate small vortices that definitely helps in keeping flow attached over the canopy!