[MVRC] GR_23

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G-raph
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Joined: Sun Jun 26, 2022 11:50 pm

Re: [MVRC] GR_23

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The second correlation issue I encountered during the 2023 season was related to flow attachment towards the back of the sidepod undercut.

Beyond the differences in total downforce and aerodynamic balance shown in my previous post, this was the most striking flowfield difference between the Fast and MVRC settings that I discovered when receiving the results of the first 2023 race.

I had developed a very aggressive sidepod for my 2023 car. It featured the usual large undercut with high inlet as well as the wing-shaped wide sidepod seen on current F1 cars. However, I also took advantage of the less restrictive Mantium Challenge rules to extend the undercut to the sidepod trailing edge, improving flow energy towards the rear suspension and beamwing.

This looked great with the Fast settings, but unfortunately much less so with the official results, where there was a large flow separation reducing energy around the floor edge and diffuser.

You can see this difference between the settings on these 2 GIFs :

- Flow velocity on an X-slice :
Image

- Flow velocity close to the car surface (but not exactly on it, as this would be 0) :
Image


For Race 02 (and 03) I decided to reduce the plan-view curvature of the sidepod, hoping this would fix the separation. However this is difficult to do when your development tool doesn’t show you the problem. This only improved the flowfield by a little bit, so for Races 04 and 05 I made further side-view changes and decided to add a large turning vane to contain the separation.

- Geometric evolution of the sidepod :
Image

- Resulting flowfield changes / Flow velocity on an X-slice :
Image

- Resulting flowfield changes / Flow velocity close to the car surface :.
Image

As a lot of other things changed from race 01 to race 05, it is impossible to quantify how much performance was recovered by fixing this flow separation.

However, giving that overall I lost downforce during the season, it is probably correct to say that the time spent on fixing this correlation issue was not worth it. :cry:

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G-raph
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Joined: Sun Jun 26, 2022 11:50 pm

Re: [MVRC] GR_23

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Final post! :o


The final correlation issue I encountered during the 2023 season was again related to flow attachment. But this time it was on the floor fences, and appeared during the season.

I started the season with a floor that was working very well. So my aim for in-season development was simply to evolve the floor design to make it work a little bit harder, rather than changing the concept.

The floor is the most important part of modern F1 cars, and the large fences at the front of it are a key element to its aerodynamic performance.
These fences turn the flow like the old bargeboards did, keeping the front wheel wake away from the floor tunnels. They also generate a lot of vorticity, and if used correctly the low pressure along the path of these vortices can greatly increase downforce produced by the floor surface.

From Race 01/02/03 to Race 04/05, I changed the main floor profile, hoping to generate lower pressure around the fences and generate stronger vortices, despite not changing the fences themselves.

- You can see how effective this was with the Fast settings used for development :

Image

- Unfortunately this was not the case with the official MVRC results, as you can see on the second GIF :

Image


The explanation for this is quite simple : the flow is now detaching at the back of the main floor fence, reducing its effectiveness. The adverse pressure gradient between the (now more intense) suction peak on the fence and the recovery pressure on the outboard floor edge had increased too much, so the flow would no longer stay attached.

Image

As well as not producing the local downforce that was expected, this had the unintended consequence of shifting the main fence vortex trajectory downstream, which you can see on the final GIFs. This more inboard vortex position de-optmised its interaction with the diffuser vortices, losing further aerodynamic performance.

Image


The 2024 season of the Mantium Challenge starts in 2 weeks, so I’d better resolve this problem before the first race!


This was the last post about the development journey of my 2023 car. Thank you for reading all of them! I hope you enjoyed them, found them informative, and maybe even inspired you to join the competition.