Toyota Celica Supra Forum banner

1 - 20 of 43 Posts

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #1 (Edited)
MKII Airflow / Pressure Rendering / 2D Model - 56K GO HOME

I'm in the process of creating pressure, temp, mach, airflow/streamline, density renderings for the MKII Supra. This is so those of us consindering chopping up our hoods for functional vents can place them in the proper position. Also one of my "bucket list" goals is to set a land speed record in my MKII. So that being said..

I'm working right now in MicroCFD, pretty much the only Windows based Virtual Wind Tunnel program I can find. It's a bitch to use, clunky, not really up-to-date, not all that configurable for sub-sonic applications, and uses a simple but DUMB-ASS shape file system where each points coordinates are listed (took me an hour and a half to manually create the damned shape file clicking one point after another typing the coordinates into Excel).

However it makes pretty pictures that make it idiot obvious where to put a hood.

Some people have pointed out that SMCars.net might have 3d models of MKII's... They do not. They have 2d blueprints.

IF ANYONE HAS A 3D MODEL OF A MKII SUPRA LET ME KNOW

I can do 3d rendering but I went to school to 1st fix computers, 2nd to do bomb disposal. Spending weeks of my life creating a beautiful 3D render of a MKII is not what I call fun.

I also plan on using the Linux based FENICS virtual wind tunnel. It does a LOT better job, dealing with 3D so we can see how the rear hatch spoilers function, how a modified rear spoiler would function (better or worse) depending on app. etc.

Now for pictures. Right now I have MicroCFD doing number crunching for the next 15 hours while it comes up with 1/10th of a seconds worth of Realtime wind-tunnel data. That's right at this rate it's going to take aobut 15 hours of data processing to create .1 second of realtime data. >.< Too bad it doesn't support clustering so I can run it on multiple PC's @ once.

ANYWAYS...

For the goods... I wasted damn near about 5 hours of my life so far on this ...

The Celica XX Blueprint I started from.


The massive AI (Adobe Illustrator trace)


Never seen this posted before.... I didn't use it as it's not proportionally correct. Look @ the nose of the car... and the camber obviously

TANYA - Can we get T-shirts made of this that says NOT A FUCKING DeLorean!! lol




Flow Tests Done @ 76.1 MPH
















50 Line Streamline


100 Line Streamline



Static Mach (Wind Speed)



Static Pressure



Much more data processing is needed. I'm going to try to get this to do number crunching @ 120mph, for about a week or so. Be very useful for thos drag racing types. That means 168 hours of full-time, non-stop cpu load, however it will hopefully let us get some more stable flow animations to better interpret where pressure zones & what pressures are @ a constant speed. Right now this animations are what happens in .1 (1/10th) of a second (accord to how I'm interpreting setting this up, I'm still new @ this).

Enjoy the results. Hopefully this should give people a better idea of where to cut holes in their hoods for proper ventilation, as well as what kind of side skirt/underbody aero might help them get better traction/times.
 

·
Registered
Joined
·
3,767 Posts
I run Linux on my home PC, if there's anything you want me to do, PM.
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #4
Will do. I'm going to have to be making some changes to the shape file, I need to remove the wheels and fix a few glitched points. Also need to figure out how to get my shape file to the BOTTOM of the wind tunnel. Right now the damn thing is smack dab in the middle, even though I'm selecting "Ground Effect"

Thanks for the offer of help. Right now I'm dual Booting to Ubuntu on my Desktop & Laptop. I'm just wanting to get as much rendering done on the laptop before the demo expires. Although I'm thinking of using WINE in Linux to install a Window App (MicroCFD) and then I won't have to worry about the damn "trial period" expiring. Sure it'll be a pain to get it properly config'd but I know I can do it :D I might get some of your help if you know a bit about WINE when it comes to that.
 

·
Registered
Joined
·
3,767 Posts
I run utorrent in wine, but I haven't really messed with wine itself.
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #6
Apparently a feature of MicroCFD is if you Pause a test (that's been running for 45 minutes into a 13- 15 hour run) to check the results, it won't resume and you have to start all over!!! HOW AWESOME. not. Glad it wasn't in the morning before work only to find out it'd still be processing when I get home from work 12 hours later.
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #9
RESULTS!!! I can haz them!

Unfortunately I've yet to figure out how to get MicroCFD to test @ speeds LESS than .8 Mach... which if you do the math is a stupid, we'll-never-see-it 608.9 MPH ... which is a bit fast. SO we can very crudely infer slower speeds from the first few frames.

Right now I have work to do on the wifes Supra, however I'll eventually post up links to the SWF flash files.

If anyone wants the AI outlines, Shape files, Slides, Test result files, LMK.















I'll be doing processing on ONLY the front bumper, hood, windshield and roof next.
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #11
so whats the pressure wave look like when a mk2 hit's the sound barrier?
Well pretty close to the second animation I posted. It was @ .8 Mach which is 608 MPH. I DID figure out how to change the speed of the wind tunnel test. I'm currently RE-running the test @ .1 Mach (76.1 MPH) which should give us a much more accurate rendering of the air flow, and pressure zones created from normal driving.

Just waiting for the number crunching to finish. My poor laptop has been running full tilt for the last 4 or 5 days doing nothing but wind tunnel testing. Thank god I don't need it for anything else. It's so CPU intesive the rest of the laptop pretty much grinds to a halt. Even on my 64-bit dual core AMD desktop it was using 100 CPU and choking it down (of course it was getting done a lot faster... but still).

Anyways looking forward to getting some real data on the MKII airflow/streamlines.
 

·
Premium Member
Joined
·
6,116 Posts
I has new wallpapers...... Great Shit, Rusty! Gonna show this to one of the locals, to drive home my point about underbody aero on his soon to come LSR Supra. Lexan Side skirts FTW!
 

·
Registered
Joined
·
9,840 Posts
Rusty, I need to buy you a beer or 3 .... Nice work.
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #15
Thanks guys. Next I hope to run tests with larger scales of the shape file. IE. The Supra bigger so we could get a better picture of air flow over the front half (Bumper, Hood, Windshield), however that's for another day.

Of note. @ 76 MPH the air under the car is moving a WHOPPING 118 or so MPH. That's nucking futs. Really. I never knew it moved that fast. It's obvious our cars can benefit from underbody side skirts. I had been thinking about making some from 1" L aluminum angle iron as a bracket, and then bolting thick rubber belting (1/4" -> 3/8") to the vertical bit of the L aluminum. That way the skirt will still be flexible enough to not get destroyed over the occasional speed bump but still stiff enough to do its purpose.

No wonder Mercedes makes a big deal about their cars being as aerodynamic UNDERbody as well as Overbody.
 

·
Premium Member
Joined
·
6,116 Posts
Knowing this, Would you suggest a diversion/blockage strategy (splitter, spoiler, skirts, and a bigass wing) , or would you use undertray tunnels and a diffuser for downforce?
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #17
All of the above would help. From what I've seen in these, a front chin splitter would help (I'm thinking approx a 3 to 4" lip, but I'm sure less would help as well). Also it would work better if it was NOT just a lip but continued up under the front portion of the engine bay as well. The side skirts will help contain the high-speed low pressure area that starts right behind where the front wheel hubs are and continues all the way back to about where the rear control arms are.

A wing is dependant on what speeds will be run, but more downforce up front would be well matched with more rear downforce. Even something as simple as adding a Gurney Flap can make a big help, and they're stupid simple. It would be pretty easy to add one to the stock MKII 84/85 wing. Though it WOULD permanantly put holes in an otherwise okay FG hatch wing.

All of the things you mmentioned will help the car stick to the ground better. Although they are in 2 different categories. The splitter/spoiler, skirts, undertray tunnels, and diffuser all promote low pressure zones, and stabilize them based off of air that's already flowing under the car. I don't see drag increasing by much with the addition of these, if anything I see it lowering (lower drag). The Wing on the other hand will increase drag, however it also greatly increases downforce, and also drag. The amount of downforce/drag is a trade off. More DF=More drag... can result in slower times, however if the power is there and the track isn't fast enough for the the drag to hurt times, then use it. It's one of those things that would need to be dialed in.


I'll put this in perspective. I know of a Miata that races Auto-X. This dude has a Lexan wing/spoiler. It's attached to the trunk lid, it's about 18" TALL, and it's the FULL WIDTH of the car. (Of course the underside is braced with aluminum strapping). But for him the amount of DF he sees at Auto-X speeds is offset by the amount of drag it creats. Obviously above 45mph that thing would almost positively get ripped off, or slow the car like a drag chute (not that much but you get the idea).

So yes, all of the above.

I think the easiest things to implement are the front chin splitter, side skirts, and a Gurney Flap on the rear stock 84/85 hatch wing.

The next step would be re-inforced sheets of FG under the car to smooth airflow with a mild inverted airfoil shape to create even MORE downforce. Added to that removal of the stock wing and a race wing added. Wing to be chosen based off of track speeds. Higher speeds can use a smaller wing. Though if you have HUGE HP you can get away with a huge wing and huge DF.

The last step would be continuing the underbody streamlining from around the rear sub-frame and adding a diffuser. This would promote a stable exit of undercar air and probably yield a top-speed increase of a few mph.

Personally I may be over zealous for suggesting it but I think vortex generators are pretty cool and don't see when more high-end exotics use them.






Along the header panel, as well as right in front of back window (like on the Mitsu EVO) perhaps on the rear 1/2's of the fender flares (or a few inches behind them) might promote better airflow.
 

·
Premium Member
Joined
·
1,969 Posts
Thank you for your efforts! We came back from an autox today, in which top speeds in the Supra were about 58 mph, with a variety of elements in the course. The 10" rear spoiler I added to the car definitely does something. Not so sure it created too much drag, but it definitely kept the rear better planted. We ran 4 laps with the rear spoiler, then 3 laps without, to compare. The front splitter had been run at a previous autox, and it too seemed to help front end grip in turns. Overall, I have seen positive benefits to the use of the splitter and spoiler at our modest autox speeds, to the point that I might need to "loosen" up the rear some, but decreasing rear toe-in.

Nice to hear your findings are pretty consistant with my experiences.

Don L.
 

·
is awesome
Joined
·
2,736 Posts
Discussion Starter #19
Glad to hear back from someone who's actually running the stuff we're discussing. I would love to see pictures of both the splitter and the wing. :D

I'm seriously thinking of purchasing MicroCFD just so I can run LOTS more simulations and wind-tunnel testing on various wing / splitter lengths & sizes.
 

·
Premium Member
Joined
·
1,969 Posts
Glad to hear back from someone who's actually running the stuff we're discussing. I would love to see pictures of both the splitter and the wing. :D

I'm seriously thinking of purchasing MicroCFD just so I can run LOTS more simulations and wind-tunnel testing on various wing / splitter lengths & sizes.
Check out my pics in the racing section of the forums. The front splitter extends forward to the leading edge of the bumper, the rear spoiler extends 10" outward from the rear hatch.
That's a bunch of awesome stuff you are doing. You will need to dumbify it down quite a bit for me to make much sense of it though :)

I'll check for the Cliff Notes version!

Don L.
 
1 - 20 of 43 Posts
Top