[MVRC] Mantium Virtual Racecar Challenge 2016

[LVDH]

Variante has been quite bad with the cooling flow this year and TF was not able to have it perfect for his first entry of this concept either, so he might not get P1 right away but if he does I bet with a gap to the next cars. Once more do not overlook Pure Power Racing (yes, he has the black car, I have made a bad mistake there). While these super sleek cars will have the least drag, JJR is my bet for P1. A rear wing has is such a good part for down force and has so much aero efficiency, I think you simply need a big one. But only if you can get it balanced with enough front down force and we all know that JJR knows how to balance a car.
The TF and Variante cars will be the way to go for Le Mans ( I assume).

Anyways as you will very soon get a much enhanced version of MantiumWFlow I am wondering what you guys think about fully using it and delaying the last race for one or two weeks. If we delay the race for two weeks you would get your results on Christmas, which might be a nice present for one of you.

[Alonso Fan]

I would welcome a two week delay to the final race because thats when I finally get some spare time!

[Ft5fTL]

It looks JJR has submitted two cars I think there is an error with the car n°31.

Nah i sold the team to JJR

[RicME85]

I won't be entering.
Having engine issues. Using Matteo's car I'm getting 40% power (with no modifications). All I have done is created the heat exchanger monitoring surface. Can only assume it's a Sketchup STL issue producing poor results like Andre showed on his site where faces can have an impact on how flow works through the HX.

If you want, you can send me the car and (knowing how that ducts work, since they are the same I used for the first race) I can help you looking for the issue.

I can provide a more complete car if you prefere. I noticed that the cooling flow dependends on the whole car, roughly:

70% energy of the entering flow (sum of kinetic and pressure energy)

10% internal duct geometry (recirculation can reduce the flow)

20% exit position (it helps if the duct ends in a low pressure area: below the rear wing or below the rear suspension cover if adequately shaped to generate low pressure).

Only point two is defined in the custom car...

Consider that into the ducts of the custom car there is a 100mm thick extruded segment, that helps the design of the heat exchanger (just fill that area and extrude): even with SketchUp it is quite easy to obtain an accurate geometry of the heat exchanger. The similation error caused by bad triangulation should not be greater than 10% in this case.

I used the input_files you supplied that included the heat exchanger. I ran a simulation with just the files you supplied and got less flow than expected (the 40%). The only change I made was to copy the front face of the heat exchanger and move it rearwards by 50mm but as its Sketchup and the way it triangulates I believe I have this issue:


I have tried a test where I made ever single triangle so that the STL exporter didnt need to but that still doesnt work.

I am going to try a test when I get the chance on a very simple non legal design to see if I can get to the bottom of things. If I cant that will be the end of my participation.

[LVDH]

Well first many guys had issues with the cooling now most cars are good, so it can work. You can send me the case for me to have a look and make sure it is not some strange OF thing going on. Variante figured out more than one way so far to get bad results and only by looking at his cases I could figure out what was going on.

[Alonso Fan]

I won't be entering.
Having engine issues. Using Matteo's car I'm getting 40% power (with no modifications). All I have done is created the heat exchanger monitoring surface. Can only assume it's a Sketchup STL issue producing poor results like Andre showed on his site where faces can have an impact on how flow works through the HX.

If you want, you can send me the car and (knowing how that ducts work, since they are the same I used for the first race) I can help you looking for the issue.

I can provide a more complete car if you prefere. I noticed that the cooling flow dependends on the whole car, roughly:

70% energy of the entering flow (sum of kinetic and pressure energy)

10% internal duct geometry (recirculation can reduce the flow)

20% exit position (it helps if the duct ends in a low pressure area: below the rear wing or below the rear suspension cover if adequately shaped to generate low pressure).

Only point two is defined in the custom car...

Consider that into the ducts of the custom car there is a 100mm thick extruded segment, that helps the design of the heat exchanger (just fill that area and extrude): even with SketchUp it is quite easy to obtain an accurate geometry of the heat exchanger. The similation error caused by bad triangulation should not be greater than 10% in this case.

I used the input_files you supplied that included the heat exchanger. I ran a simulation with just the files you supplied and got less flow than expected (the 40%). The only change I made was to copy the front face of the heat exchanger and move it rearwards by 50mm but as its Sketchup and the way it triangulates I believe I have this issue:
http://mantiumchallenge.com/wp-content/ ... g_flow.png

I have tried a test where I made ever single triangle so that the STL exporter didnt need to but that still doesnt work.

I am going to try a test when I get the chance on a very simple non legal design to see if I can get to the bottom of things. If I cant that will be the end of my participation.

That's only an issue on your side. Lvdh sorts it out when he runs the simulations. All my heat exchanger faces are made in Sketchup. Obviously when I start running my own simulations, I'll have bad results but lvdh sorts it out before running the official simulations, so you could have still submitted

[RicME85]

Whats the point?
If its my side then I cant configure my car.

[RicME85]

Well first many guys had issues with the cooling now most cars are good, so it can work. You can send me the case for me to have a look and make sure it is not some strange OF thing going on. Variante figured out more than one way so far to get bad results and only by looking at his cases I could figure out what was going on.

You have enough of my cases, I sent you three the other day

[Alonso Fan]

Whats the point?
If its my side then I cant configure my car.

Hmmm true

[LVDH]

OK, I will have a look as soon as all the MVRC simulations are done.

A first look at the log files from your support questions shows me that your cooling should be fine. Are you sure that you are looking at the right number and not maybe at the exhaust pressure? Keep in mind that those simulations did not run to the end as I only looked if they work.

[RicME85]

engine_intake, 6.63477[Pa*m^2]
engine_exhaust, 0.134772[Pa*m^2]
mSurf_HX_monitor, -1.9966[m^3/s]

engine_intake, 6.68382[Pa*m^2]
engine_exhaust, 1.151[Pa*m^2]
mSurf_HX_monitor, -1.47861[m^3/s]

engine_intake, 7.18295[Pa*m^2]
engine_exhaust, 0.146202[Pa*m^2]
mSurf_HX_monitor, -1.66251[m^3/s]

[LVDH]

Are these the results from the solver log or what the post-processing tool tells you?

[RicME85]

They are from num_cfd_results_mvrc.

For comparison here is the data from the cfd results file and solver log.

engine_intake, 6.63477[Pa*m^2]
engine_exhaust, 0.134772[Pa*m^2]
mSurf_HX_monitor, -1.9966[m^3/s]

faceSource faceSource_engine_exhaust output:
areaIntegrate(engine_exhaust) for p = 0.0680237

faceSource faceSource_engine_intake output:
areaIntegrate(engine_intake) for p = 3.3182

faceSource mSurf_HX_monitor output:
areaNormalIntegrate(sampledSurface) for U = (-1.00847 0 0)

[LVDH]

Ok, from which of the cases you sent me is this?

[RicME85]

Non of them as they didnt finish. The ones I sent were from second PC that was failing to complete. Those figures are from main PC which has no issue.