[MVRC] CCE GP001

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machin
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[MVRC] CCE GP001

Post by machin » Fri Sep 06, 2019 11:05 pm

So, as part of the new 'Grand Prix' style cars in the Mantium Virtual Racecar Championship I created a basic car... initially just to check that the rules "worked", but also to offer as a starting point for anyone who wanted to join the championship but felt daunted by the idea of making a full car... You can download these parts here:-

Basic Car

CCE_Sidepods_v7 (includes Heat Exchanger and carrier plate parts).

Updated front Wing

...As it turns out I don't think anyone used the car... but it was submitted as a non-points-scoring entry for the 1st race anyway.

As many may have seen on the main MVRC topic; we never intended to make the cars exactly like F1 cars... but there is clearly a resemblance there.... to make the rules and rule-checking easier we have much simpler rules... in some areas this means there are more constraints than the real F1 cars, and in others we have more freedoms... I'm pleased with the way the rules have worked out; we had some great cars submitted for the first race, with some really nice features...

...The same can't be said of my car... :) It was intentionally simple; no trick features, just a simple two element front wing, a basic "traditional" shaped diffuser with no strakes, a simple floor and one barge board element. It wasn't CFD test beforehand, so I had no idea about it's aerodynamic performance.

Image

As part of the submission to each MVRC race you get back a CFD report which includes 100's of images showing pressure plots, velocities, streamlines, etc, here's a few examples:-

Image
Image
Image

There are also 5 key aerodynamic characteristics which determine each cars performance:-

Drag coefficient (x Area) = 1.03m^2
Downforce coefficient (x Area) = -1.119 m^2
Centre of Pressure = 1.91m
Sidepod Cooling Flow = 2.447m^3/sec
Air intake Pressure integral
Exhaust Outlet Pressure integral

The sidepod cooling flow was a little less than needed (3.0m^3/sec), which meant the car was down on power.. whilst it had a reasonably low drag, it also had very little downforce.... On the positive side the balance was pretty good... (optimum COP is 1.85m).

The pressure plots clearly show where the problems are;

1, The upper elements of the front wing are producing no downforce at all: essentially they are aligned with the flow coming off the lower element, and as such are not imparting any momentum change to the air flowing around them.

2, The diffuser isn't really creating much downforce; again, not surprising since the car had a gently sloped diffuser with no strakes; so there's a lot of untapped energy in the diffuser.

Clearly there are lots of other areas that could be improved too.... but for the second round I didn't want to make any drastic changes (and as a non-points-scoring entry I am not trying to win the champinship -not that I could even if I wanted; the top teams really are very good!);I just wanted to make some basic changes to see how much difference they would make.

The first thing however was to address those terrible aesthetics: a sleeker nose and more streamlined head protection... just because the original looked awful... :oops:

The basic sidepod design remained the same, but with a bigger inlet, and large heat exchangers (achieved by installing them at a flatter angle, allowing them to be 'taller')... hopefully that would address the power loss....

The front wing gets new upper elements with more curvature, and the diffuser gets a 'double-inflection' profile and a couple of basic strakes...

Image

I'll post an update after I get the results from the second race, which will occur shortly.

The competition is still open to new competitors.... I think it's a great thing to do if you are interested in racecar aerodynamics... it would look great on your CV if you're an engineering student, it's another way to practice your CAD skills, or finally if you're a frequent forum poster explaining where the real F1 teams are going wrong, here's your chance to prove you really do know what you're talking about :wink:

Go to www.mantiumchallenge.com for entry instructions and rules.
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Maritimer
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Re: [MVRC] CCE GP001

Post by Maritimer » Sat Sep 07, 2019 2:04 am

I'm interested but am having a hard time figuring out what software is needed. Is it just the one program or do you have to also have AUTOCAD/something similar? What about computing power? I'm a first year MET student so 3d modeling is going to be a big part of what I do, would make for good practice.

Zynerji
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Re: [MVRC] CCE GP001

Post by Zynerji » Sat Sep 07, 2019 2:37 am

Looks like the standard CATIA background. Or possibly SolidWorks.

machin
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Re: [MVRC] CCE GP001

Post by machin » Sat Sep 07, 2019 7:00 am

Any 3D CAD program should be ok... I just used FreeCAD, and it’s running on a a little netbook computer!

You can also download the CFD program, which is free for participants... now that does require some reasonably good computing hardware, and even then the analysis takes some time... but you can just do what I’ve done here; just rely on the official CFD analysis from each race...
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CAEdevice
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Re: [MVRC] CCE GP001

Post by CAEdevice » Sat Sep 07, 2019 9:01 am

Good car!
I had initially underestimated it: considering that the download is available, I recommend it to everyone as a starting point.

Tzk
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Re: [MVRC] CCE GP001

Post by Tzk » Thu Sep 12, 2019 7:56 pm

You could also try to design with Fusion360 as autodesk provides a startup/hobbyist version of it at no cost.

machin
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Re: [MVRC] CCE GP001

Post by machin » Sat Sep 28, 2019 10:57 pm

OK... so the second round didn't go quite as hoped.... The main problem was the cooling was worse.... It seems that we as a community have now realised that the heat exchangers can't be laid too flat.. that design has two detrimental effects: the lower portion near the floor becomes restricted by the floor and the act of turning the air through an "S" shaped path through the heat exchanger creates enough of a restriction that the air simply goes around the sidepod instead...

But anyway, the minor changes to my car between rounds 1 and 2, and their effects on the surface pressures can be seen below:-

Image
Image

It's clear to see that there was a small increase in pressure on the upper surface of the upper front wing elements (plus the additional little winglets mounted to the endplates).... but the lower surface of the front wing shows almost no change.

The diffuser, despite the additional strakes, looks to have a slightly worse performance too...

So for Round 3 I have tried to resolve the cooling issue: the inlet is again bigger, the sidepod cross-section is now almost at a maximum by the heat exchanger (i.e height and width just within allowable volume), the sidepod is not as long, I have cut a big hole in the upper surface and the Heat Exchanger is now far more upright.

I also have now gone for a simpler front wing (using elements very similar to my rear wing); this gives higher angle of attack of the upper element, but they're now shorter (the thinking being that I don't want to restrict air getting to the sidepods).

I've also added a second pair of diffuser strakes, but the diffuser profile is the same as round 2. Fingers crossed...


Image

The complete car (in stl format) can be downloaded here:-

CCE Round 3 Model

It’s in constituent parts... so anyone can use this as a starting point and replace the parts one by one as you design your own.
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machin
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Re: [MVRC] CCE GP001

Post by machin » Tue Oct 08, 2019 8:51 pm

So... cutting the holes in the top of the sidepod made a big difference... and the big tall plumes now emanating from them show just how much of a restriction was caused by the original tight "slalom" route the air had to take through the heat exchangers and then through the duct; with the holes on top of the sidepod the air now takes a much smoother flow, and that has resulted in a doubling of the flow!

...On the downside these plumes are now seriously affecting rear wing performance!

Image

So, something of a compromise between the two would seem to be a good idea.... :)
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CAEdevice
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Re: [MVRC] CCE GP001

Post by CAEdevice » Tue Oct 08, 2019 8:57 pm

Thanks for sharing. I am more interested in what happens in the front wing area: in my car most of the cooling flow comes from below the front wing (and it is a problem because it is disturbed by the suspensions arms, so I added winglets to keep it below the suspensions).

CAEdevice
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Re: [MVRC] CCE GP001

Post by CAEdevice » Tue Oct 08, 2019 8:57 pm

About the rear wing: a T wing could help to clean the flow.

machin
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Re: [MVRC] CCE GP001

Post by machin » Tue Oct 08, 2019 11:08 pm

CAEdevice wrote:
Tue Oct 08, 2019 8:57 pm
... in my car most of the cooling flow comes from below the front wing...
Well, my front wing (particularly the underside) doesn’t work very well, so there isn’t much upwash... it’s pretty clear that I need to use more elements as that mainplane is just asking for too much direction change in one go. ☺️

Probably if I sort that out it will work more like yours... however for now I need to sort the rear out as COP is really bad... 🙁
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hollus
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Re: [MVRC] CCE GP001

Post by hollus » Wed Oct 09, 2019 5:38 am

machin wrote:
Tue Oct 08, 2019 8:51 pm
So... cutting the holes in the top of the sidepod made a big difference... and the big tall plumes now emanating from them show just how much of a restriction was caused by the original tight "slalom" route the air had to take through the heat exchangers and then through the duct; with the holes on top of the sidepod the air now takes a much smoother flow, and that has resulted in a doubling of the flow!

...On the downside these plumes are now seriously affecting rear wing performance!

Image

So, something of a compromise between the two would seem to be a good idea.... :)
Any reason why those plumes from the top of the sidepods cannot be directed outwards as well as upwards, thus clearing the rear wing and maybe, just maybe, hitting the rear tires?

It is awesome when you MVRC guys publish these changes in the open. Very thought inspiring! Thanks!
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MadMatt
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Re: [MVRC] CCE GP001

Post by MadMatt » Wed Oct 09, 2019 8:15 am

Indeed, have you tried to exit the radiator flow on the outside rather than upside ? That way you could "merge" it with the sidepod flow towards the rear, between the rear tyre and centre part of the car

variante
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Re: [MVRC] CCE GP001

Post by variante » Wed Oct 09, 2019 3:30 pm

MadMatt wrote:
Wed Oct 09, 2019 8:15 am
Indeed, have you tried to exit the radiator flow on the outside rather than upside ? That way you could "merge" it with the sidepod flow towards the rear, between the rear tyre and centre part of the car
I did, and it compromised the flow towards the diffuser. It might work anyway...i can't say which solution is the best one in absolute terms but, in the end, if you manage to control the upwash with some optimization, you're ok.

Machin, try with an array of flaps:
Image


hollus wrote:
Wed Oct 09, 2019 5:38 am
Any reason why those plumes from the top of the sidepods cannot be directed outwards as well as upwards, thus clearing the rear wing and maybe, just maybe, hitting the rear tires?
That would be interesting. MVRC regulations are quite literally tight around the rear end of the car, but maybe we'll see some cars with that layout before or later. But you would need an impressive downwash to compensate for the loss of the Coke bottle shape (like the RedBull from 2012/13).

wb92
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Re: [MVRC] CCE GP001

Post by wb92 » Wed Oct 09, 2019 3:55 pm

hollus wrote:
Wed Oct 09, 2019 5:38 am
Any reason why those plumes from the top of the sidepods cannot be directed outwards as well as upwards, thus clearing the rear wing and maybe, just maybe, hitting the rear tires?

It is awesome when you MVRC guys publish these changes in the open. Very thought inspiring! Thanks!
I think flow which passed radiator won't have enough energy to reach rear tyres and clear it out, I don't think with current set of rules that might be possible
variante wrote:
Wed Oct 09, 2019 3:30 pm
Machin, try with an array of flaps
I agree, Machin - you should try it out to control outflow of the radiator ;)
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