Hey guys I wanted to ask. We are seeing a lot of vortices coming off the rear wing , but how come none ever come off the front?
my theory is is that the front wing is more efficient, and designed better, as opposed to the rear wing, which is unavoidable for certain edges etc where it comes from??
Its still there, its just rare for it to be visible. Whenever you have a wing that is generating a pressure difference between the upper and lower surfaces, it will trail out a vertex behind it. The front wing probably actually has worse vortexes relative to its size as it has a lower aspect ratio, but they are used to actually do something useful on the front wing as they can be used to help shape flow over the rest of the car.
Ground effect increases the pressure difference between the high and low pressure side. Vortexes are created when those 2 sides mix at either end of the wing. So no, ground effect would also increase vortex strength (AKA induced drag).
Because front wing endplates are located in front of front wheels, while rear wing end plates are located above and backwards from rear wheels (there is no pressure mounting behind them, as it happens in front of front wheels - behind front wing endplates).
This is R29 or R30 CFD, I'm not sure. It explains it better than any words.
Lycoming wrote:Ground effect increases the pressure difference between the high and low pressure side. Vortexes are created when those 2 sides mix at either end of the wing. So no, ground effect would also increase vortex strength (AKA induced drag).
Uhh no, Ground effect increases the pressure difference *by destroying those vortices*.
Those vortices exist because air is spilling from the high pressure side to the low pressure side. Ground effect occurs when that vortex hits the ground and can't get all the way round. Because the vortex can't get all the way round, less air spills over, and a higher pressure differential is created.
There isn't a whole lot of air spillage over the wing itself, the endplates take care of that. nowadays, vortices generally form behind the wing, but they still produce drag as a result.
Ground effect in cars is primarily due to the venturi effect sucking air through the wing, increasing flow speed on the low pressure side.
Tip vortices are not a sign of an efficient wing. They are a sign of a wing working hard.
They are an unavoidable side effect of having a wing, but the car is shaped to work with the front wing vortices, i.e. the whole flow through and around the side has a benign inter-relation with the vortices such that, in addition to aerodynamic benefits within this flow, the vortices are made smaller and weakened to the point of invisibility. The designer is using up some of the vortex energy to manipulate the flow. Everything is designed to affect everything else, in a good way, until, downstream of the rear wing, nothing can be done.
So the front wing vortices are weaker the those from the rear wing.
This is 3 dimensional flow, difficult to visualise.
Tip vortices are detached flow phenomena, which persist long after the car has passed. The car is just dumping energy from the rear wing.
In flying vortices can persist for a mile or so, in modes equivalent to F1 'high downforce', such as landing or violent manouvres.
Last edited by Tommy Cookers on 15 Apr 2012, 22:32, edited 1 time in total.
