Cancelling trailing vortices, is it possible?

[freebeard]

I don't understand what you are saying freebeard.

Nor I, just thinking out loud. It went from talking up The Whit [ignore] to serrated edges to an anti-reversionary strategy. Similar to the Tesla one-way valve or anti-reversionary exhaust headers. The rear-facing aspect would be a faceted vortex trap.

Prolly more like Air-tabs.

[JulianEdgar]

Originally Posted by M_a_t_t

Would the basic idea not transfer to the vortexes made by a road car? Is it because there is (I'm assuming) a lower difference in pressures of the road car than the wings on the F1? Which probably means the effect on the F1 is much greater than a road car and so isn't high on the fix-it list on road car aero.

Well my point I guess is that wings are designed on F1 cars to give huge downforce, and so they are going to have major problems with wingtip vortices. On normal road cars we don't have that issue. Therefore, their solution I doubt will help us.

Care to share (briefly or detailed) those experiments? My first thought when posting was maybe for the a pillar, a wing tip placed in front of the windshield to try and lower the effects of the a-pillar vortex as it seemed easier to alter.

The aerofoil guide plates I made for the Insight's A pillars helped considerably in reducing the upward motion of the tufts on the side glass behind the pillars, so presumably reduced vortex formation from this source.

I tried corrugated egg cartons stuck vertically in front of the separation point on the side of the Insight ie designed to give more progressive separation and so reduce the pressure change. They didn't seem to work.

Do you think your failure with the rod and tuft could be attributed to the less-uniform wind on the road, the scale of the car (vs a model), or just a difference in execution?

I don't know. But even when you can 'see' vehicle vortices (revealed by smoke, leaves, etc) they don't look anything like the idealised versions in the textbooks. I have a strong suspicion that much less is understood about these vortices than is often suggested. For example, I ran a large open mesh grid behind a car, the grid covered in tufts. The tufts revealed nothing.

[JulianEdgar]

Originally Posted by Vman455

In the 2nd edition (1984), pp. 56-62, with some more discussion in the next section on fastbacks pp. 62-65.

Interesting - I didn't think I remembered anything about cancelling of vortices and it appears that material is not in my edition (first edition - 1975).

[Vman455]

I guess that material must have been added by Sykes then. The jacket says he joined City University in 1965 and became Head of Department in 1982, and that the second edition is "revised" by him.

[M_a_t_t]

Originally Posted by JulianEdgar

The aerofoil guide plates I made for the Insight's A pillars helped considerably in reducing the upward motion of the tufts on the side glass behind the pillars, so presumably reduced vortex formation from this source.

I tried corrugated egg cartons stuck vertically in front of the separation point on the side of the Insight ie designed to give more progressive separation and so reduce the pressure change. They didn't seem to work.



I don't know. But even when you can 'see' vehicle vortices (revealed by smoke, leaves, etc) they don't look anything like the idealised versions in the textbooks. I have a strong suspicion that much less is understood about these vortices than is often suggested. For example, I ran a large open mesh grid behind a car, the grid covered in tufts. The tufts revealed nothing.

Are you referring to this testing?



I'm having a hard time visualizing how you would've had the setup with the egg carton. Do you have a picture?

Interesting. Especially with the mesh.

[JulianEdgar]

Originally Posted by M_a_t_t

Are you referring to this testing?



I'm having a hard time visualizing how you would've had the setup with the egg carton. Do you have a picture?

Interesting. Especially with the mesh.

Yes the above pic. If I could get the extrusion in longer lengths, I'd run it permanently.

Egg cartons (looks like I didn't test total drag but just pressure change behind separation edge).

[AeroMcAeroFace]

Those guides put on the C-pillar/D-pillar would probably reduce the vortex rotation, but that may be a bad thing. The vortex can help with flow attachment or reattachment.