Quote:
Originally Posted by Hermie
According to a French study (Peugeot/Citroen), the large counter-rotating vortices I'm getting are really reducing rear lift while also slightly reducing drag.
Their tests show that vortex generators are MUCH more effective at reducing lift than drag, and the large counter-rotating vortices I'm seeing on my rear window means that the VG's are doing their job quite well:
"It appears that the largest drag and lift reduction is clearly associated to a strong increase of the size of the recirculation bubble over the rear slant."
Here's the paper:
SpringerLink Home - Main
This is exactly what I want- Reducing lift, with drag reduction as an added bonus. |
By moving the separation point rearward,the base pressure is increased in the wake when it does occur,reducing both drag and lift as a consequence.
Circulation of any form is robbing your gas tank,as this kinetic energy cannot be converted to static pressure which leads to lower base pressure and higher form drag.
The VG is a palliative for inherently inefficient designs.
The Kamm-back offers no horizontal surface in the aft-body where lift can occur,as it moves all the 'lift' directly behind the vehicle,eliminating any vertical component.Also,the longer the tail,the smaller the wake,higher the pressure,and lower the drag.And no lift.
If you'd like to see a perfect low-drag,low-lift roofline,GOOGLE an image of the Ford Mk IV race car of the mid-1960s.It has a textbook Kamm body and track-proven stability.