Exhaust Blown Floor - Forward Exhaust Exit

[Formula None]

It is a great video, so thanks TURU. I assume the pit crew just makes sure to stand clear of the center of the car when it comes in.

[shelly]

That's pretty conclusive.

I do not think so. It is obviuous that exahusts will go laterally when the car is stationary, but that does not imply anything about their path when the car is moving.

[PlatinumZealot]

Butt shelly, would you say that by putting in the initial angle into a CFD model then solving it, an a good approximation of the path of the gas can be made? Under the car can only have so little pressure.

[shelly]

I think it is quite tricky to simulate in cfd.
But if we take into account that air under the floor is travelling at more than 120% car speed and that is far denser than exhausts, then deflection of the exhausts by the flow will be significant. Influence of low and high pressure zones in the car will be felt and force the exhausts inward

[DaveW]

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.

Interestingly, perhaps, if I had wanted to generate lift (upwards aero force), I would have tried to create vortices with the directions shown in your diagram. This reference contains a classic illustration of my point. I'm unsure of the overall effect on your model, but I would guess (with apologies) that your vortices might not be the most efficient aerodynamic solution for maximising downforce.

[tpo4444]

You could clearly see gasses blowing out up front in the wet in Canada yesterday in an off-throttle condition. Very cool.

[Giblet]

That's pretty conclusive.

I do not think so. It is obviuous that exahusts will go laterally when the car is stationary, but that does not imply anything about their path when the car is moving.

Of course, but there was much debate about their initial angle.

[ringo]

That's pretty conclusive.

I do not think so. It is obviuous that exahusts will go laterally when the car is stationary, but that does not imply anything about their path when the car is moving.

It does. It even more extreme than i thought. That is 90 degrees.
That wont go under the floor at any cost.

If it did, the exhausts would choke. I am telling you this as a fact, i wont go into detail unless i am asked.

But let me just say that a flow bending over 90 degrees out of a pipe is almost equal to blocking it with a plate. It just wont happen.

Fluid side skirt theory is like Charlie Sheen right about now.

[Formula None]

I am telling you this as a fact, i wont go into detail unless i am asked.

Please go into detail.

That's pretty conclusive.

I do not think so. It is obviuous that exahusts will go laterally when the car is stationary, but that does not imply anything about their path when the car is moving.

Of course, but there was much debate about their initial angle.

Really? From the very first photos at testing, the pipe opening could be seen clearly seen from the side views. Although I guess we don't think we really know how many different exhaust tip vanes & exit angles iterations they've tried over the course of the year.

The squashed aspect ratio of the video might be playing with some people's perceptions of the plume angle, but still, it seems obvious to be near perpendicular.

[PlatinumZealot]

The thing is those CFD's are as close as anyone on the internet is gonna get. There are no other real practical was of solving this. We can talk over it all day, but "anything is anything."

[ringo]

I think it is quite tricky to simulate in cfd.
But if we take into account that air under the floor is travelling at more than 120% car speed and that is far denser than exhausts, then deflection of the exhausts by the flow will be significant. Influence of low and high pressure zones in the car will be felt and force the exhausts inward

That was automatically accounted for in the cfd.

The air under the floor is denser in truth, but it is actually helping the cause.
The exhuast position is in such a way that it cannot be defflected inward by anything on the inside of it, which is the flow under the car in your situation.
That is only possible if the floor is sucking it, which is not happen.

It wont and cannot force the air to bend 90 degrees and go under the floor.

A sharp 90 bend in any fluid stream requires a lot of force.
If you look at plumbing, and if you know how much force the water puts on the elbow when it changes direction, you could see why those kinds of angles are unnatural in free flow.

There is little or no examples in nature where a flow is not only turning 90 degrees by another flow, but reflexing to angles over that amount and holding its general shape.

I think Renault are learning to increase the virtual size of their floor as the season progresses. That may be an explanation for the increasing angles.


Shelly tell me; why do you feel compelled to support a certain argument because it came from above the likes of anyone in these forums?
Even when it has no logical support, just stamp of approval from the media.

Notice none of them are coming back in here with the F1 big boy quotes anymore?

F1 technical needs a Peter Windsor episode, we got more F1 info on here than anywhere else.

[shelly]

n_smikle, when I say cfd I think of professional, not amateur cfd.

ringo: I do not know why you keep saying that it is evident that the flow would not go under the floor, when there's no evidence at all.
Still you keep saying I am wrong without understanding what I write, and this is more worrying than annoying.

I have seen in your previous posts that you do not discuss with logic, but you often yield to insulting other people.

[ringo]

Let's just say this CFD is as good as it's going to get from anybody on any F1 forum, or outside an F1 team.

The chances of coming across this info is almost non existent.
This exhaust technology is not documented elsewhere.

F1T has supported documentation and imagery.



So i still don't see why you rather hear say over blatant evidence.


I think i should push for this theory to find it's way on an F1 show of some sort.

Someone get a guest Aerodynamist onto the site, or put this on the Peter Windsor show. I'm camera shy , but someone can take the theory and images and probably question a guest F1 engineer about the R31 car, if Peter gets one on his show. Ask me first though for the proper way to ask the questions, so they give accurate answers.

[xpensive]

If air-speed under the floor is some 120% of outside the same, there will be a difference in static pressure according to;

p1 - p2 = Rho * (v2^2 - V1^2) / 2

A numerical xample; If the car is travelling at 80 m/s and airspeed under the car is 120% of that, pressure diff is 1.7 kPa,
which over an estimated 2 m^2 translates to a downforce of 3400 N. Seems to me shelly's numbers are in the ballpark?

All in all, said pressure diffential alone should be able to suck at least some of the xhausts in under the car?

[shelly]

@ringo: it is not haer say against evidence. But if you do not want to discuss because you can not put on the table something more solid than "it's in the images", then ok.

You have not recognized a F1 areodynamicist (SLC) even when he posted on this forum, so probably even if you get to chat with another one, you will question their opinion if it forces you to rethink your approach.

@expensive: biggest role in deflection is played by the flow on the side of the car, travelling at a little higher sped than he car's.
Then there is low pressure under the floor, and even lower pressure in the kink line region.