Khamsin Virtual Racecar Challenge 2015

[sjns]

Good luck to everyone! I wasn't able to work on my car as my bachelor thesis is in it's final weeks. So I won't be participating this round. I'll be back for the last race!

[LVDH]

MantiumRAY has released pictures of the newest car:



It only had some three additional days of work done since the last race. I can only hope it will repeat previous results.

[CAEdevice]

It is an evolution of the lastest race winner car: do you expect a df/drag ratio above 5?

[LVDH]

I hope so. But due to my trip I could not work too much on the car and discovered a huge mistake with the floor before submitting the car so a last minute fix on that was necessary. It costs a tenth of a second on the test track.

[CAEdevice]

I could reach df/dr = 5.1 but with a cop around 2.0, so I submitted a less efficient car (maybe 4.3).

[LVDH]

It is an evolution of the lastest race winner car: do you expect a df/drag ratio above 5?

I am afraid not. I have received the results. This time they did not quite match my expectations. Drag is pretty much as expected but downforce is a bit off. Also CoP is further backwards than expected. I think that I found the main issue. Looking at the diffuser air flow in the "official" results there is quite a large recirculation zone. I had the same issue in race three but not to this extent:
My results:

KVRC results:


I guess for the next race I will need a less extreme diffuser. I will have to put some work on getting my simulations to match the KVRC results better.

Now I am a bit pessimistic about the race results.

[CAEdevice]

Don't worry: I received the result and they are even worse then yours.
350N simply lack the total, almost all concentrated on the floor.

Well, it is not a problem, it's game, but much less funny than it could be.


LOCAL SOLVER (OCCFD running on windows, based on OpenFoam 2.2), df/drag = 4.39
Drag: 1634.31 N
Drag coefficient - Cd: 0.88
Drag area - Cd.A: 1.36 m2
Downforce: -7172.38 N
Downforce coefficient - Cl: -3.85
Downforce area - Cl.A: -5.98 m2
CoP of downforce: 1.590 m along streamwise (Y) direction from Y = 0.00 m.
KVRC Only: Corrected CoP of downforce: 1.620 m along streamwise (Y) direction from Y = 0.00 m.

OFFICIAL RESULTS (Amazon server, maybe based on OpenFoam 2.3), df/drag = 4.15
Drag: 1648.41 N
Drag coefficient - Cd: 0.88
Drag area - Cd.A: 1.37 m2
Downforce: -6822.19 N
Downforce coefficient - Cl: -3.66
Downforce area - Cl.A: -5.69 m2
CoP of downforce: 1.589 m along streamwise (Y) direction from Y = 0.00 m.
KVRC Only: Corrected CoP of downforce: 1.619 m along streamwise (Y) direction from Y = 0.00 m.

[MadMatt]

Matteo, looking at the results, it cannot just be the floor or the CoP would have been moved forward, but it remained the same.

[CAEdevice]

Matteo, looking at the results, it cannot just be the floor or the CoP would have been moved forward, but it remained the same.

I mean that portion of the floor that is about 1,5-1,7m from the front wheels, about centered on the COM.

[RicME85]

Amusing you guys have the results and my car was in two weeks before deadline

[LVDH]

You see, we are just faster

[MadMatt]

Sorry for my ignorance, but looking at the regulations I am confused about 4.1. As I understand, an area of 60'000mm^2 has to be created, and then a 180'000mm^2 area that is coplanar with the first one? But how far from the 60'000mm^2 surface this bigger surface has to be?

[cdsavage]

Sorry for my ignorance, but looking at the regulations I am confused about 4.1. As I understand, an area of 60'000mm^2 has to be created, and then a 180'000mm^2 area that is coplanar with the first one? But how far from the 60'000mm^2 surface this bigger surface has to be?

The 180K area ("area template") must be coplanar with the rear face of the inner template. The inner template is an extrusion of the inlet shape rearwards along the normal for a distance of 500mm to 1000mm, so the area template is anywhere between 500mm and 1000mm rearwards of the inlet.

[MadMatt]

Sorry for my ignorance, but looking at the regulations I am confused about 4.1. As I understand, an area of 60'000mm^2 has to be created, and then a 180'000mm^2 area that is coplanar with the first one? But how far from the 60'000mm^2 surface this bigger surface has to be?

The 180K area ("area template") must be coplanar with the rear face of the inner template. The inner template is an extrusion of the inlet shape rearwards along the normal for a distance of 500mm to 1000mm, so the area template is anywhere between 500mm and 1000mm rearwards of the inlet.

Thanks, I understand now!

[cdsavage]

The entries for round 5: