Exhaust Blown Floor - Forward Exhaust Exit

[ringo]

car doesn't seem to be working well in monaco.


should they switch to the rear exit exhausts?

[sknguy]

I'm sorry if this had been discussed, I couldn't find any discussion. But what I'm curious about is how the hot exhaust gas and the cooler air might mix, or not. Does temperature, density and viscosity effect their interaction? And does any of this help to create the boundary, or skirt? Also, could another intention be to replace/displace the cooler, denser air that would normally leak into the system with the lower pressure, hot gas?

[Formula None]

From Spain (speed unknown, assume car is decelerating at this point):

[godlameroso]

@sknguy exhaust is a pulse even if it seems continuous, every pulse(which has thermal and kinetic energy) is followed by a low(er) pressure pulse, as these pulses enter the free air stream, they separate. They then follow their corresponding pressure gradients, which is why some of the combined flow(of exhaust and free stream air) go over the car, and some goes under.

Also from the pics Formula None posted it seems that the area of the beam wing with the upper side element of the diffuser create a huge chunk of downforce, you can see the hot air being aimed upwards by that region. Perhaps since pullrod suspension cleans up some of the suspension parts that are in the way of the top side of the diffuser, it improves it's efficiency somewhat, compared to pushrod suspension.

What Renault has done is distribute the overall downforce of the vehicle more evenly, than if you used a conventional exhaust configuration. Yet, overall downforce is limited because you no longer have the exhausts to mix with the hot air from the cooling systems, which limits the amount of downforce you can create at the rear. On the plus side, it seems to have a larger effect on reducing drag than would otherwise be possible.

I think that if Renault learns how to exploit the hot air from the cooling systems, they could gain some performance.

[malcolm]

Judging by the flames and the heat waves, I'd say a lot of the heated air/exhaust finds its way through the diffuser.

Either that, or someone spent a lot of time photochopping that to claim an internet victory.

[ringo]

You have to be kiding.
There is a fire on the right of the car. Where there is fire there is smoke and heat.
That is not coming from the exhuast.

Secondly, if there is a leak in the exhuast, you can expect heat to come from where that leak is as well.

You can see the fire ball right bellow the wing. That's not exhuast, that's just a renault r31 burning to the ground.

[strad]

Ringo
+1

[Ferraripilot]

That's not exhuast, that's just a renault r31 burning to the ground.

LOL. Sorry, but that just sounds funny and I had to say so. Carry on.

[malcolm]

That's not exhuast, that's just a renault r31 burning to the ground.

True, good call. Shoulda spent more than 2 seconds thinking about it.

[TURU]

[youtube]http://www.youtube.com/watch?v=z6W7nLXoVUA[/youtube]

.... it blows under the floor you say.
I know the flow will be deflected at speed, but when you look at the above video...

[Giblet]

That's pretty conclusive.

[Formula None]

Well, as has been pointed out many times in this thread, we can't look at photos, CFD or videos taken at a single airspeed and assume the exhaust interaction would be the same at all times. I don't think anyone's ever doubted the exhausts shoot out the side when the car isn't moving, I mean, you can literally see the exits from the side of the car. The question has been whether or not the exhaust plume moves under the car at speed.

[strad]

Well, as has been pointed out many times in this thread, we can't look at photos, CFD or videos taken at a single airspeed and assume the exhaust interaction would be the same at all times. I don't think anyone's ever doubted the exhausts shoot out the side when the car isn't moving, I mean, you can literally see the exits from the side of the car. The question has been whether or not the exhaust plume moves under the car at speed.

And at this point there is very little doubt....or that at speed it flows along the edge forming a seal.

[Powerslide]

i havent seen anyone talking about vortex because i believe thats what the target was..study the vortex of a sports prototype as it is used to run on the side walls creating an air wall behind the car boosting diffuser.

[img] http://img828.imageshack.us/img828/7610/81672810.jpg [/img]

[PlatinumZealot]

That video is a good one because you can see the initial angle of the exhaust. The initial angle of the exhaust can be used to make the CFD simulations more accurate. A CFD of hot air in a cross stream should be very simple.

I am actually surprised that the exhaust comes out at such a transverse angle.