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Re: Khamsin Virtual Racecar Challenge 2016
Posted: 11 Feb 2016, 21:29
by CAEdevice
variante wrote:Looks good...a nice evolution of last year's car. I spot a couple of details that i'm going to use on my car
Why the black livery?
The black livery is only to hide some details
It is more (or less, it depends on the point of view) than an evolution: it is the same SWX file of the 2015 car renamed and with some parameters changed!
AratzH wrote:Veeery nice looking CAEdevice!!
I was wondering, what flow/pressure drop or velocity/pressure drop curve and porosity did you use for your tests? I am having some trouble to comply with the rules with the parameters I am running...
Thank you! Honestly I don't remember, but I have the data written somewhere: I will let you know tomorrow (anyway: we really need some more data to replicate option 2 in occfd).
Code: Select all
EDIT: Here are the porosity data (completely guessed!). The software is KARALIT CFD (see the article linked above).
- media porosity = 0.5
- scalar porous permerability = 6x10^-8
- Darcy velocity = 10
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 11 Feb 2016, 22:18
by pierlu99
I'd like to participate to the new Introductory class, but it's fine if I do not subricribe yet to the challenge, but post photos here on this topic of my car?
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 11 Feb 2016, 23:32
by CAEdevice
pierlu99 wrote:I'd like to participate to the new Introductory class, but it's fine if I do not subricribe yet to the challenge, but post photos here on this topic of my car?
There is no reason to not post the images of your car even if you did not subscribe (except that you would reveal your "secret weapons" !). But why to wait for the subscription?
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 12 Feb 2016, 13:53
by machin
Looks awesome: I think the new sidepod design looks much more realistic for 2016 if this is anything to go by.... I also really like the low nose/crash structure on this car compared to last years car.... Have you noticed much performance difference from that configuration...?
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 12 Feb 2016, 16:30
by pierlu99
CAEdevice wrote:pierlu99 wrote:I'd like to participate to the new Introductory class, but it's fine if I do not subricribe yet to the challenge, but post photos here on this topic of my car?
There is no reason to not post the images of your car even if you did not subscribe (except that you would reveal your "secret weapons" !). But why to wait for the subscription?
I prefer to first have a good car and then maybe start the challenge.I have read the rules , but once I made the car,can I show you that in a private messages for some advice ? I have some ideas, but I do not know if they are legal...
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 12 Feb 2016, 17:46
by CAEdevice
machin wrote:
Looks awesome: I think the new sidepod design looks much more realistic for 2016 if this is anything to go by.... I also really like the low nose/crash structure on this car compared to last years car.... Have you noticed much performance difference from that configuration...?
Yes, from the design point of view, 2016 will be much more interesting, especially if we think about the "effciency" tracks.
About the nose: 2015 version allows to send high energized flow under the floor: this helped because I had balance issues (low rear df). This year I hope to have more df from the rear part of the car, so I choosed the low nose solution that is a bit more efficient (df/dr ratio).
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 12 Feb 2016, 17:50
by CAEdevice
pierlu99 wrote:CAEdevice wrote:pierlu99 wrote:I'd like to participate to the new Introductory class, but it's fine if I do not subricribe yet to the challenge, but post photos here on this topic of my car?
There is no reason to not post the images of your car even if you did not subscribe (except that you would reveal your "secret weapons" !). But why to wait for the subscription?
I prefer to first have a good car and then maybe start the challenge.I have read the rules , but once I made the car,can I show you that in a private messages for some advice ? I have some ideas, but I do not know if they are legal...
It is ok for me. Also consider that the first race will bring no points, so it could be a good legality check.
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 09:10
by pierlu99
ok perfect, in a couple of days I'll start to build the car
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 09:16
by machin
I thought I should post this here too;
machin wrote:Finally... I got around to compiling this stuff into an "Introduction to Racecar Aerodynamics Guide".... its aimed at KVRC beginners and doesn't have any maths in it!
Introduction to Racecar Aerodynamics
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 10:33
by CAEdevice
machin wrote:I thought I should post this here too;
machin wrote:Finally... I got around to compiling this stuff into an "Introduction to Racecar Aerodynamics Guide".... its aimed at KVRC beginners and doesn't have any maths in it!
Introduction to Racecar Aerodynamics
Well done! I think that the performances of the new teams will improve thanks to this.
About vortex generators: I am convinced that a finer mesh would be needed to use them to improve the diffuser. At the moment the big vortices that pass through the diffuser are generated by the air coming from the side and matching the longitudinal flow, but they are "big" vortices (100mm diameter). With a finer mesh (cell dimension reduced under the floor and diffuser) smaller vortices (the ones you showed in the pictures of the document) could be used.
I looked for an image of the "big vortices": consider that the distance between the strakes under the diffuser is about 120-140mm.
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 10:46
by machin
I was having a play a little while back using Khamsin and a reasonably corse mesh and I saw some fairly decent improvements using vortex generators in the throat of the diffuser.... That might have been due to the basic diffuser itself being rubbish though!
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 11:24
by CAEdevice
Interesting! I use the following rule (empiric): to model directly a 100mm vortex, I need a mesh with cell dimension no bigger than 10mm, but maybe I am pessimistic
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 14:06
by RicME85
What sort of size vortex generators are we talking?
After reading the guide, I had some ideas but that depends on the size the VG's would need to be (large - would there be space or small - 10mm rule)
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 18:22
by AratzH
Code: Select all
EDIT: Here are the porosity data (completely guessed!). The software is KARALIT CFD (see the article linked above).
- media porosity = 0.5
- scalar porous permerability = 6x10^-8
- Darcy velocity = 10
[/quote]
Thanks for the info CAEdevice, I will se how I can compare it with what I was using.
Now, regarding the rules, I would need some clarification regarding rule K4.1: option 2. When the rule states: "The heat exchangers may be rotated from a forwardfacing orientation by no more than 30 degrees. " can we asume any axis to perform the 30deg rotation or has it to be done in one of the coordinated axes (X, Y, Z) ?
Re: Khamsin Virtual Racecar Challenge 2016
Posted: 13 Feb 2016, 18:33
by CAEdevice
I thinks it means the angle between a plane normal to the car direction and the heat exchanger plane.
I think that option2 has to many limits (inlet/outlet areas, heat exchanger inclination, heat exchanger surface). I would prefer a completely free option (with flow minimim requiremetns of course)