F1technical.net

godlameroso wrote:If that was all there was to it, Williams should be a top 10 team not fighting off the Lotuses

Note that i said tried, not actually did. That a look at their sidepods. And of course that's not all there is to it (hence the 'general') but it helps and is worth pointing out.

Hi Everyone,

We ran this analysis a week or two ago now, and were a little confused by the result.

We were wondering if anyone could explain it for us.

We ran a whole rear end section of the car through some CFD, at 75ms^-1, which is around 150mph.

The results, especially in the diffuser area, are very odd.

The stepped floor section has probably had a large drag penalty, which won't occur on the real car, due to the splitter section, so I won't post any figures for the analysis.











We ran the analysis with a ride height of 25mm, but the diffuser doesn't seem to be doing anything, can anyone explain why this is?

Is it just because we don't have a floor, and the stepped section of the diffuser is ruining the result?

Tom.

because you do not have the floor in front. You would get much better results with the whole floor. The whole floor itself has to be there to achieve ground effect, now it is just an concave shaped plane

Tozza Mazza, please, learn something about aerodynamics before designing your own F1 car. CFD is useless without solid theoretical backup.
If u need some help about aerodynamics u can send PM to me.

Don't be so hard on the guy. Tozza I think you answered your own question, the car works as a whole, the only part you could really do CFD in isolation is probably the rear wing. Even that gets slightly affected by the way the airbox draws in air. I think your rear end is looking good, keep up the good work, and don't give up despite what others say. Just attempting to design an F1 car is a huge learning experience, especially for a small team of people.

With a complete floor, you would see the pressure increase at the leading edge of the floor, drop slightly, and continue until the diffuser, where the pressure decreases in relation to the rest of the floor. It's this combined pressure difference that is technically doing the work.

Well, I didnt want to push on him. I just want him to understand that there are lots of people on many forums (including this one) who know a lot about aerodynamics. And before spending lots of your time on doing something, isn't it wise to ask about how it works from someone who knows? Rather than being dissapointed in the end that u were totally wrong.

Thanks for the info Godlameroso, I guessed that was the issue!

In response to Sonic59, I know the basics surrounding aerodynamics.
I understand the principles behind aerofoils, and understand that it's all about pressure differentials, and understand how a vortex works, but my knowledge is limited.

There are a lot of people on the site, who can help me, this is what I'm after!

What am I going to be wrong about? I haven't made a statement, and you cannot have a 'wrong ' design, (apologies if this is a misunderstanding, if English isn't your first language).

I am still only at college, and plan to study aeronautical engineering at Uni.
This design project is for the purpose of learning more about aerodynamics, not for giving up on. I believe there is a lot to be learnt from this project, and it does present an oppurtunity for testing out some ideas we have.

Tozza Mazza wrote:



We ran the analysis with a ride height of 25mm, but the diffuser doesn't seem to be doing anything, can anyone explain why this is?

You say you ran with a ride height of 25mm, but these results don't look like there is any sort of solid surface there at all. Are you sure you tried to model the road?

Good point,I should have explained, and thought I had!

We ran an analysis after this one with the ride height, but the results were pretty much the same (we know that's because of the lack of a floor), then again, we were only looking at diffuser pressure at this point.

I can get some for you (I think), But there is little difference between the two analysis (I haven't actually seen the analysis with ride height), But I can't be certain that images are available.

Thanks.

Ok, yeah, the field results with the road should reveal some of the deficiencies I think. Note that your wings don't seem to be working very well in the above. It's a little hard to see because the images are small, but you appear to be getting premature separation on the flaps of the main wing and the beam wing. This won't be helping your efficiency.

horse wrote:Ok, yeah, the field results with the road should reveal some of the deficiencies I think. Note that your wings don't seem to be working very well in the above. It's a little hard to see because the images are small, but you appear to be getting premature separation on the flaps of the main wing and the beam wing. This won't be helping your efficiency.

Yeah, Seperation does seem early, and looks like its to do with the position of the slot gap, this will be changed on the next wing, which we probably won't run until we have the whole car made up. The beam wing seems to be suffering from exactly the same thing.

Tozza Mazza wrote:...I know the basics surrounding aerodynamics.
I understand the principles behind aerofoils, and understand that it's all about pressure differentials, and understand how a vortex works, but my knowledge is limited.

Limited indeed. Vortexes (at least using them) should be a secondary concern until all other principles are solidly in place.
By reading the above, I get the feeling that said knowledge comes from looking at airplane principles, as it keeps coming back to this forum. It can't be stated enough, that an F1 car is not an airplane, it does not work in the same environment as a plane, it doesn't have the same constrains and it doesn't have the same targets as a plane. The effect of the lack of a floor on that diffuser above illustrates the point well. So, while the laws of physics are the same as for planes, the design directions are not.

Tozza Mazza wrote: I am still only at college, and plan to study aeronautical engineering at Uni. This design project is for the purpose of learning more about aerodynamics, not for giving up on. I believe there is a lot to be learnt from this project, and it does present an oppurtunity for testing out some ideas we have.

But with that attitude, you should learn lots overtime. Thumbs up.

hollus wrote:

Tozza Mazza wrote:...I know the basics surrounding aerodynamics.
I understand the principles behind aerofoils, and understand that it's all about pressure differentials, and understand how a vortex works, but my knowledge is limited.

Limited indeed. Vortexes (at least using them) should be a secondary concern until all other principles are solidly in place.
By reading the above, I get the feeling that said knowledge comes from looking at airplane principles, as it keeps coming back to this forum. It can't be stated enough, that an F1 car is not an airplane, it does not work in the same environment as a plane, it doesn't have the same constrains and it doesn't have the same targets as a plane. The effect of the lack of a floor on that diffuser above illustrates the point well. So, while the laws of physics are the same as for planes, the design directions are not.

Tozza Mazza wrote: I am still only at college, and plan to study aeronautical engineering at Uni. This design project is for the purpose of learning more about aerodynamics, not for giving up on. I believe there is a lot to be learnt from this project, and it does present an oppurtunity for testing out some ideas we have.

But with that attitude, you should learn lots overtime. Thumbs up.

Thanks, I understand that, and hey, I'm here to learn, I know that ground effect plays a key part in the interaction with the aerofoils, and the lack of floor mistake is a big one, and does explain a lot.

I know a bit more than that about aerodynamics (Flow seperation, Drag (frontal area and what not), stall, and flow attatchment), but my knowledge is basic, and I'm trying to build on it.

I personally am in the opinion you should add at least a piece of floor in front of it, for example make the floor really short with the floor's splitter, I think by that way you get an idea and decent results of how your floor will work and it's interaction with the wing. An diffuser does barely anything without the floor properly simulated and the floor attached to it.

Also it is great to say you want to learn! Being quite similair here I came to the forum in 08 barely knowing anything about aerodynamics, now 3 years later I know I have learned a lot, too bad I could not apply this to my study since I do not meet the requirements to do such an study. I really hope you will be able to do the study, and maybe in 10 years or so we have a new Newey on the grid.

Looking good Tozza