F1technical.net

xpensive wrote:@ ringo, just take things from the top and share your xhaust input data with us, how difficult can that possibly be?

xpensive wrote:Would it be too much to ask for input data to the above images, such as xhaust density, specific heat capacity, massflow, xit-speed and xit-temperature, ambient temperature, pressure and relative speed; Finally the software and processor used?
...

Nevermind the ambient stuff, I can figure that out myself, but I need the car-speed.

70m/s the same as the road surface, to be precise the wind speed. It's basically like a wind tunnel.
I hid the road surface for clarity. I have another video with the speed increasing from 30m/s and up, I'm yet to upload it.

Click to enlarge

BreezyRacer wrote:

conni wrote:i dont know if you are aware but the renault engines shut down cylinders during certain corners and in the pits to save fuel but they do use a lot of oil and have to use a reserve tank as the engine cant carry enough

conni

I can believe they shut down cylinders for traction control out of some corners and of course pit speed limits .. no problem there .. but are you implying that all F1 engines don't use a dry sump with external oil tanks?

TC is banned, so doing so for traction control out of some corners would be illegal IMO.

Conni didn't imply that the Renault engine was alone in having an external oil reservoir, he said that they need to ALSO use a reserve tank, presumably because running on fewer cylinders leads to greater than normal friction/wear.

Could this be the first signs of a McLaren FEE?

Here's a close-up:

FEE car accelerating from 30m/s

[youtube]http://www.youtube.com/watch?v=8CtLB7g5s9s[/youtube]

exhaust blows very wide at low speed for this car specifically.
The heat stays clear of the tyres, so it's not an issue at low speed where slower air wont be able to cool the gases quickly.

As the speed increases the momentum of the oncoming air redirects the momentum of exhaust gases and pushes in line with the car.

the stream of air passing from the nose to the pipe, is not the exhaust air, it flows along the edge of the pipe, i forgot to takes those out, so they can be ignored.

I shouldn't have change the camera angle initially, i was trying to find a good angle so you can see slightly underneath, the 3/4 view is actually better, but you can see the gases are completely clear of the car in the beginning of the video.

Cute images, such a shame they mean less than zilch as long as you ignore to present the input data for the xhaust flow.

Look how the turning vanes (the metalic part) are shaped in the photo I posted above. Seems the exhaust are not directly blowing under nor over the floor

Note how the barge board and the floor turning vane are now connected and the large "tunnels" for the exhaust to travel under the floor.

Regarding CFD simulation (not only Ringo's nice work, but more in general): can the pulsating nature of the exhaust gases be simulated by CFD code?
Also, can you simulate transient events where not only the exhaust flux but also the car attitude is modified, e.g. the car 'squatting' as the driver starts to reapply throttle at a corner exit?

These kind of transients would surely be important in assessing the potential of a concept like FEE before committing to actually implementing it on the car.

xpensive wrote:Cute images, such a shame they mean less than zilch as long as you ignore to present the input data for the xhaust flow.

I guess the issue here is that we don't actually know the real car's exhaust flow or temperature... Ringo has taken a stab at them and doesn't want to turn this whole discussion into "you've used a temperature which is 5 degrees higher than it should be, and 5% less flow than it should be.... blah blah blah"

X, you could help by posting what flow rate and temperature you would've used?

Onch wrote:Regarding CFD simulation (not only Ringo's nice work, but more in general): can the pulsating nature of the exhaust gases be simulated by CFD code?

Yes excel files can be input into the simulation and the flow will map from it.

Also, can you simulate transient events where not only the exhaust flux but also the car attitude is modified, e.g. the car 'squatting' as the driver starts to reapply throttle at a corner exit?

That's the thing with solidworks you can't move the bodies that are being tested. You can simulate rotation and simple translation of symetric surfaces like drums or roads, but you can't actively move the model. ANSYS can though.

ringo wrote: That's the thing with solidworks you can't move the bodies that are being tested. You can simulate rotation and simple translation of symetric surfaces like drums or roads, but you can't actively move the model. ANSYS can though.

Ah OK, I was not sure that the fluid mesh could be modified during the calculation runs. I guess this does not speed up the process though...

ringo wrote:FEE car accelerating from 30m/s

[youtube]http://www.youtube.com/watch?v=8CtLB7g5s9s[/youtube]

Super video. Thx for the work well done, Ringo

I don't see the benifit of the exhaust stream exiting the floor. Maybe they have small fins on the underside where the exhaust enters, which direct the flow in a way, that it stays below.

machin wrote:

xpensive wrote:Cute images, such a shame they mean less than zilch as long as you ignore to present the input data for the xhaust flow.

I guess the issue here is that we don't actually know the real car's exhaust flow or temperature... Ringo has taken a stab at them and doesn't want to turn this whole discussion into "you've used a temperature which is 5 degrees higher than it should be, and 5% less flow than it should be.... blah blah blah"

X, you could help by posting what flow rate and temperature you would've used?

I'm sorry to ask this, but can you redirect the exhaust flow (angle) until it stays underneath just to see if it does have an affect in the area of the diffuder? I believe this to be crucial in how this system is supposed to work.

I don't think you have the shape of the exhaust flow entrance point in your model. It seems to be shaped to bend and keep the flow under the floor. Btw, this is not a request to change your model just a thought on how to come by a visualisation on what makes this thing work.

xpensive wrote:Cute images, such a shame they mean less than zilch as long as you ignore to present the input data for the xhaust flow.

The inputs are very minimal, presets make up the most of the data if you are satisfied with them. I'll give you a print screen to satisfy you.
Most of the input is the mesh settings. That determines how accurate the simulation is.
Why do you think i'm trying to deceive?
I don't use this laptop to do the sims, it's too slow. As soon as i get time later today i'll show the inputs.

horse wrote:http://i79.servimg.com/u/f79/14/79/55/26/_q0c8212.jpg
http://i77.servimg.com/u/f77/12/07/06/50/jpg_ds10.jpg

Note how the barge board and the floor turning vane are now connected and the large "tunnels" for the exhaust to travel under the floor.

Do you think there is a tunnel under the bulged turning vanes ?
If it's the case, I don't think so. the turning vane contains a thick side crash structure, that's why it's bulged. But its bottom is flat.

http://i69.servimg.com/u/f69/14/79/55/26/monaco10.jpg
http://i69.servimg.com/u/f69/14/79/55/26/071wri10.jpg