[MVRC] Mantium Virtual Racecar Challenge 2020 (Grand Prix Cars)

[Ft5fTL]

Excellent work, that is how to climb to the top. Wasn't it you with the OF mesh morphing? Did you get somewhere with this? If I ever find the time, I would like to show how to parametrize geometries, hook it up with a Python optimizer and optimize the car. But if one of you guys can do it, even better.

Yup! But I have only used it very little on the car. It is quite hassle to setup, and the results are not always great. I am rewriting the whole thing in python (univerisity licenses dont last forever ) with a new approach which should give higher quality morphing and a lot more control. I want to make it available to MVRC contestants when I am done.
Here is an example, original case (left) and morphed case (right):
https://i.imgur.com/jP74WSa.png
And force convergens looks like this:
https://i.imgur.com/GeHQIq5.png

This looks interesting. Sadly i dont know where to start.

[etsmc]

I think i am getting a massive area of recirculating air causing issues with diffuser flow again but it seems to start at ground level and work its way up and into the diffuser.

Do you think you would be happy to share an image or two which leads you to the conclusion that the air is recirculating -(I’m not disagreeing with your conclusion, but I hope that posting an image might help others to give you some constructive feedback )

Happy to post some images when I get a moment.
Having said that I think I have fixed the issue.

I had a kick up in the floor in front of the rear tyre that went all the way from the outside floor edge across to the edge of the mandatory floor edge. I have now pulled this back so it is only going from the outside floor edge and as wide as the tyre.

So rather than pulling air up at the inside edge of the tyre it now flows straight above and below the floor and the rear tyre squirt seems to be smaller.

UPDATE:
I seem to have overwriten the original images so here are a couple of artist impressions one at ground level and one at floor level. then also one of the floor kick up.




Now its more like this


[https://mercurymotorsport.files.wordpre ... -after.png[/img]

so this fix has now shifter my COP back from 0.824 to 1.277 so still need to find some more downforce at the rear.







I feel it has to be mainly in the floor but my rear wing is probably a little low on the downforce side at cl-0.4

sorry its a bit pic heavy but if you would like more just ask!!

[jjn9128]

Good that you've fixed your floor issue. I'd say -0.4 on the rear wing is very low, you should be able to at least double that.

[machin]

...pictures...

Interesting...we really need those LIC plots as part of the image pack don’t we as they’re really useful... (Sorry Andre!)

One thing I do note is that you are using what we might call a “traditional” diffuser shape, rather than the “Double Inflection” type that most others use....I’m not saying that will instantly get you more Performance (I can’t get mine to work!)... but that must be a worthwhile avenue for development...?

[LVDH]

Interesting...we really need those LIC plots as part of the image pack don’t we as they’re really useful... (Sorry Andre!)

I know, but I can simply not figure out how to create them with VTK. I have a few failed approaches behind me. If somebody can hack something together, I can immediately add it to MFlow.

This improvement on the etsmc car is very cool. It shows that an analytical approach can only get you so far, in reality there is simply a lot of trying out that needs to be done. In this case such a small modification improved the diffuser so much that the car was significantly changed. Thank you very much for sharing.

[etsmc]

Happy to share more if people want to see.
This is actually my diffuser from 2019 that i tried after i could not figure out what was going on with the new diffuser.
I will go back to my 2020 diffuser as that was looking better that the 2019 one untill i forgot about adding the kick up on the floor.

One thing i did note on the rearwing front was that most seem to be running a triple element setup. May be an avenue of investigation.

[jjn9128]

Happy to share more if people want to see.
This is actually my diffuser from 2019 that i tried after i could not figure out what was going on with the new diffuser.
I will go back to my 2020 diffuser as that was looking better that the 2019 one untill i forgot about adding the kick up on the floor.

One thing i did note on the rearwing front was that most seem to be running a triple element setup. May be an avenue of investigation.

I'm going back to 2 Your rear wing elements don't appear to have much camber. Try increasing that before adding the complexity of an extra element.

[etsmc]

Not that anyone asked but here goes.
Simulation with the 2020 diffuser has finished and its a bit interesting
overall there was a small increase in drag and downforce bringing the cl/cd down by 0.033 and shifting the COP forward 0.026
however, the floor and plank efficiency both rose cl/cd of the floor was up 2.537 and the plank up 5.754
interestingly the floor shifted the downforce rearward by around 0.015 but this was counteracted but an overall increase in lift from the body by 0.026 mainly at the rear.

A couple of images to compare


looking at this it seems to be the top of the floor near the side pods having a larger area of high pressure.


i think i will go back to the 2019 diffuser and continue development from there.

and just a little bit more for those interested in the rear wing here is a cross-section out near the endplates.

[Thomas2019]

Could you share a picture of the mesh for that rear wing shot, please?

[etsmc]

Could you share a picture of the mesh for that rear wing shot, please?

how would I do that?? is it a paraview thing?? working on windows with paraview 5.4.1 so if you can give me steps to do it i will, and i only run the fast template with the base cell size set to 0.75

[Koldskaal]

Could you share a picture of the mesh for that rear wing shot, please?

how would I do that?? is it a paraview thing?? working on windows with paraview 5.4.1 so if you can give me steps to do it i will, and i only run the fast template with the base cell size set to 0.75

It's in Paraview under Representation, the same place you choose between "normal" surface and surface LIC. you can choose "Surface with edges" to display the mesh.

[etsmc]

Could you share a picture of the mesh for that rear wing shot, please?

how would I do that?? is it a paraview thing?? working on windows with paraview 5.4.1 so if you can give me steps to do it i will, and i only run the fast template with the base cell size set to 0.75

It's in Paraview under Representation, the same place you choose between "normal" surface and surface LIC. you can choose "Surface with edges" to display the mesh.

Thanks

[machin]

That’s a very low overall angle of attack on your rear wing... the flow stays very easily attached... so you can definitely go a lot higher on the angle... (add more camber to the two elements, or add a third element, maybe?)

[jjn9128]

and just a little bit more for those interested in the rear wing here is a cross-section out near the endplates.
https://mercurymotorsport.files.wordpre ... /06/rw.png

Can I ask what wing profiles you use? Do you use known ones or design your own?

[etsmc]

and just a little bit more for those interested in the rear wing here is a cross-section out near the endplates.
https://mercurymotorsport.files.wordpre ... /06/rw.png

Can I ask what wing profiles you use? Do you use known ones or design your own?

Only use known profiles. Never been able to draw something up in sketchup that works. Cant remember which one i started with this time sorry.
I have finished running a case with a sl1223 at an angle similar to the pofile in the image and both downforce and drag are up and the efficiency is only down by 0.5, only seen the numbers so far so once i get back to work and can have a look at the post processing and paraview will i be able to see if i can work the air more with the rear wing..
Cop is now back in the 1.35 range.