Nacelle Strake Vortices – The Irrefutable Proof of Zone Theory of Lift. Nacelle strakes are located on the front cowlings or nacelles of all modern jet engines, and create vortices that become visible in favourable atmospheric conditions. The paths of these nacelle strake vortices flawlessly give away the physical form of the pressure zones (Fig-3 below) produced by a moving wing, proving the zone theory of lift. The figures and pictures below clearly show the paths of these vortices, starting from the nacelles over to the top of the wing at increasing airspeeds, during various stages of takeoff. Notice that the vortex gets closer to the wing due to vacuum enhancement, as airspeed increases. These vortices not just only prove the existence of the subduction and induction zones over the airfoil wing, but also clearly delineate the exact shape and location of the zones, as postulated in the theory. This pattern of nacelle strake vortices, is the undeniable proof of the creation and existence of the induction and subduction zones by a moving airfoil and shows, not just that they exist, but also their shape and their location over the airfoil as well. Thus, now the theory is a fact and clearly explains, beyond the shadow of any doubt, how an airfoil generates this hitherto mysterious, but marvelous force of lift. Nacelle Strake Vortices pattern is the irrefutable proof of the Zone Theory of Lift.

Fig-1: Nacelle Strake Vortex Paths at different Airspeeds

Fig-2: Airfoil Functional Pneumatic Surfaces (deflector, inductor, lifter) Leading edge A, Trailing edge B, and C zero-slope line where inductor and deflector merge.

Fig-3: Induction & Subduction Zones Created by a moving Airfoil Wing

Referring to Fig-1,2 & 3, and images below, it is clear that subduction zone deflects the vortices around itself, and not allowing them to come into contact with the leading edge (A) and deflector surface of the wing, even in the immediate vicinity of the nacelle strakes. The vortices then follow the subduction zone envelope (as predicted by the zone theory) and then get pulled in by the induction zone vacuum, towards the wing inductor surface. The lift generating vacuum gets more and more intensified with increasing airspeed (as predicted by the zone theory of lift), until it is able to pull the vortices in, and touch the wing top, at the confluence of the two zones where they merge into each other over the wing.

Pic-1:

Rotation and Takeoff at V1.
Nacelle strakes generate vortices which follow the outer envelope of the subduction zone moving towards the inductor surface of wing top, but not touching the wing.

Pic-2:

Increased airspeed creates wing clouds over the induction zone, pulling the vortices with greater suction. Vortices start getting closer to the wing top inductor surface in the proximity. The airspeed is still not sufficient enough to create a full wing width subduction zone.

Pic-3:

Airspeed increases further, and vortices get sucked by the increasing vacuum in the induction zone and touch the wing top, merging with the wing clouds. If airspeed is high enough to stretch the subduction zone from the leading and trailing edge, the vortices follow the subduction envelope and remain over the top of the entire wing until dissipated after trailing edge, as shown in Pics-4 & 5, below.

Fig-4: Vortex high air speeds

At higher speeds approaching cruise, it is predicted that the bow wave or the subduction zone totally overlaps the induction zone along the entire chord of the airfoil. The induction zone gets sandwiched between the subduction zone and the inductor surface, but continues producing lift, above the inductor. Pics-2, 3 4 & 5 clearly show this is exactly the case, as predicted by the zone theory.The subduction zone extends so far back from leading edge to trailing edge, that it precludes any vortex touchdown over the wing top, high air speeds. See Pic-4 below.

Pic-4: Vortex Paths at Takeoff and higher airspeeds

Pic-5: Vortex path at Landing Airspeeds

Pics 4 & 5 above, show the nacelle strake vortices of a real aircraft during takeoff and landing, respectively. They can be seen skipping over the wing entirely, in both instances. The airspeed is well above the rotating airspeed V1 which enables the wing to enter far ahead into its subduction zone (the red shape in Fig-4) thereby stretching it from the leading to the trailing edge. These vortices always follow the outer envelope of the high pressure subduction zone, which is completely overlapping the wing at such speeds. The vortices are therefore repelled away and can’t come into contact with the wing’s top inductor surface, which swiftly moves ahead from beneath them. See the purple vortex path predicted by the zone theory for airspeeds 2V1 and greater, as in Fig-4 above. Nacelle Strake Vortices – The Irrefutable Proof of Zone Theory of Lift.

In future posts we will discuss more on wing icing patterns and their relevance to the zones, particularly the rime-ice formation on leading edges as shown below.