(KVRC) Variante

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RicME85
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Re: (KVRC) Variante

Post by RicME85 » Mon Mar 21, 2016 4:39 pm

That front wing :shock:

machin
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Re: (KVRC) Variante

Post by machin » Mon Mar 21, 2016 4:40 pm

Looks awesome, as always... Looking forward to seeing the numbers!
COMPETITION CAR ENGINEERING -Home of VIRTUAL STOPWATCH

CAEdevice
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Re: (KVRC) Variante

Post by CAEdevice » Mon Mar 21, 2016 6:09 pm

Well, you won the last edition and you call your car "Rancore"? What would have happened if you were finished fourth for two years? :)

Great car as usual. I noticed a small attack angle for boht front and rear wing.

variante
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Re: (KVRC) Variante

Post by variante » Mon Mar 21, 2016 7:29 pm

Thanks!
RicME85 wrote:That front wing :shock:
Hopefully this year it's not going to be oversized (actually, it could be undersized...as long as the simulations i've done with OCCFD 2.3 were reliable enough)
CAEdevice wrote:Well, you won the last edition and you call your car "Rancore"?
Sounds badass pronounced in english, doesn't it? :lol:

LVDH
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Re: (KVRC) Variante

Post by LVDH » Mon Mar 21, 2016 10:06 pm

variante wrote:
CAEdevice wrote:Well, you won the last edition and you call your car "Rancore"?
Sounds badass pronounced in english, doesn't it? :lol:
Well it seems even Magaritha is a possible car name.

What happened with the center section of your front wing?
Did you manage to get some beneficial vertices to travel along the car?

variante
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Re: (KVRC) Variante

Post by variante » Mon Mar 21, 2016 11:58 pm

LVDH wrote: What happened with the center section of your front wing?
Did you manage to get some beneficial vertices to travel along the car?
That's a duct to increase airflow to the cooling inlet. After this preliminary race, i'll decide whether to keep them or get rid of them and play with wing tip vortices.
About vortex management in general, there isn't much at the moment, but I want to try to create and control a complex system for the diffuser, hopefully in time for the first point scoring race.

BTW are you really struggling with time to get a new car ready or is that just a..."strategy"? ;)

LVDH
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Re: (KVRC) Variante

Post by LVDH » Tue Mar 22, 2016 9:37 am

variante wrote:BTW are you really struggling with time to get a new car ready or is that just a..."strategy"? ;)
Well apart from some strolling around Mulsanne's Corner I have not started working on the 2016 car. And as will will most likely not have much time soon, for the first real race I might enter an improved version of the reassembled 2015 car I entered for the pre race as the numbers look very good.
Yet nobody knows if you created a new monster which wipes everything out in the first race and sends everyone back to the drawing boards.

variante
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Re: (KVRC) Variante

Post by variante » Tue Mar 22, 2016 5:57 pm

LVDH wrote:Yet nobody knows if you created a new monster which wipes everything out in the first race and sends everyone back to the drawing boards.
Nono, don't worry about that...it's a good car, but not spectacular (yet!) as it's far from being optimized. For the moment it is just a good platform where to start developing.
I think it's going to be kinda tight, this pre-season race at least...for what is worth...

variante
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Re: (KVRC) Variante

Post by variante » Sat Sep 17, 2016 6:09 pm

Hi guys, this is a general aerodynamics analysis of my virtual race car, competing in the Mantium Challenge, born on the ashes of the KVRC. The car itself is very similar to the KVRC one (that you can see in the previous posts) and features only small adaptations for the slightly revised technical regulations of the new championship.

To the core of the post…

On the surface of the car are represented the velocity field and vector field of the airflow. The circles point out the most critical areas of the car, where the airflow doesn’t behave as predicted or at its best:

Image

Black Circle
Problem: very large area of stagnation and turbulence. It slightly increases drag values over that part of the bodywork and decreases airflow quality to the following aero elements, which aren’t many, nor important, luckily. So, despite its entity, the performance loss is not significant.
Cause: the pressure gradients impose a very steep airflow angle at the leading edge of the sidepod, the which can’t handle it at laminar state for much. Airflow separation happens and propagates over the rest of the bodywork, which is not designed to recover from such situation. Also, the exhaust pipes don’t point perfectly tangentially to the bodywork surface, so they enhance the problem.
Solution: F1 style vortex generators should solve the problem, but mesh quality around that area may not be high enough to reproduce accurately the vortices. Another solution, adopted during the last race (and abandoned for no reason…), is the use of a “slat” on the leading edge of the sidepod.

Blue Circle
Problem: turbulent area just in front of a downforce producing device.
Cause: non ideal airflow direction.
Solution: rounding the edges just behind the wheel should do the job.

Orange Circles
Problem: non ideal flow direction and velocity over the wheel arches.
Cause: unexpected airflow direction in proximity of the wheel, possibly caused by wheel rotation.
Solution: airflow can hardly be deflected towards the ideal direction, so a slightly different arch geometry is needed, with greater and more gentle radiuses on the upper edges.

Purple Circle
Problem: high speed and low pressure air causing lift over a surface that should, instead, produce downforce.
Cause: up washed air from the front wing meets a sharp edge that happens to be shaped as a vortex generator (f-18 style). The thus created vortex decreases air pressure.
Solution: rounding the edges might decrease the problem entity, getting rid of the vortex; however, the new and rounded surface could act as a wing, still generating lift. Instead, re-shaping the whole section with a gentler geometry could solve the problem, but it would decrease front wing performance. Therefore, a trade-off should be studied.

Red Circle
Image
Problem: early flow separation and dirty flow from one wing to the other.
Cause: high angle of attack of both airfoils without re-energizing boundary layer slots.
Solution: a better disposition and coupling of the two elements would help. However, it must be said that such flow separation was predicted, and that such airfoil disposition is not necessarily bad. In fact, it gives much more downforce in comparison with a traditional wing (the downside is that it produces much more drag as well, but it doesn’t really matter on the Monaco track, where it raced), especially with the kind of wing that the regulations allow you to produce: maximum two airfoils enclosed in a tight box.

Now, let’s move on to a fast comparison with one of last season’s strongest car, Mantium’s car...
Image
Image
This cuts are taken at the height of the rear wheels.
The most interesting and important area is in between the tires and near the ground, the diffuser area. That is something I already talked about in my previous post, underlining its huge importance as well as the importance of vortices for the control of flow detachments.


Image
Image
In this other comparison it is interesting to notice that even when clean air is fed to the radiator, recirculation just in front of it is still possible, unfortunately. That is caused by the really high “flow resistance” of the radiator itself. A proper sidepod duct design is important to solve this crucial issue. As this is a huge topic, it may need a dedicated post...

Comments or questions? Did I miss something?

CAEdevice
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Re: (KVRC) Variante

Post by CAEdevice » Sat Sep 17, 2016 7:57 pm

Yes, I think there is a issue with that black areas !

Seriously, I am surprised about that rear wing. Were you desperately looking for rear downforce? I have the opposite need (but I am desperate too).

Your car works well in my opinion: the choice of a front wing instead of a very extended front diffuser (mine ends behind the front wheels axle) reduced the upwash issues in the cooling inlets areas.

variante
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Re: (KVRC) Variante

Post by variante » Sun Sep 18, 2016 12:16 pm

CAEdevice wrote:Yes, I think there is a issue with that black areas !
Must be a bug or something... :D
CAEdevice wrote:Seriously, I am surprised about that rear wing. Were you desperately looking for rear downforce? I have the opposite need (but I am desperate too).
The laptime difference is very, very small. Still, I wanted to try that wing to gain some experience for the F-SAE championship, where we are indeed in desperate need for rear downforce. ...and also to introduce something new and original to this challenge.
CAEdevice wrote:Your car works well in my opinion: the choice of a front wing instead of a very extended front diffuser (mine ends behind the front wheels axle) reduced the upwash issues in the cooling inlets areas.
Yeah, that area works surprisingly well in comparison with Mantium's "diffuser" (which is the only comparison I can make, because of lack of data...). I guess the expansion behind the wing/diffuser is treated more gently by my wing; I also suspect that front suspensions interactions are quite important.

LVDH
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Re: (KVRC) Variante

Post by LVDH » Tue Sep 20, 2016 8:39 am

This is excellent. We need much more articles like this.
A few words on the comparison with the MantiumRacer. The images are from a report I created last year with geometry I was not too worried about showing to the KVRC competition. So the floor is one I never raced. Also the radiator flow resistance is much higher than what you now have in MVRC.

What surprised me when I saw the report on your car were all these non-perfect areas you have now pointed out. As Matteo's car looks very good, I think his best work so far, you will easily catch up with him.

What you point out in your black circle can be seen on every MantiumRacer. I never figured out how to get rid of it properly, so I am looking forward to see your solution.