Just-Right's Splitter and Canard Development - Update 28-8-2018

J

just-right

Member
I thought it would be good to share a project I have been working on. Although very beautiful I have always felt the Z4M styling could do with a little more aggression, especially the front. I decided to design and develop my own splitter and canards for more of a CSL/GTS appearance. Having been able to reverse engineer the car over the last year with use of photogrammetry I am approaching the development slightly differently by utilising computational fluid dynamics simulations. Below are two pictures of the reverse engineering model and the base CFD simulation

REVERSE-ENGINEERING-CROP.jpg

CFD-Start.jpg

So far I have run three different splitter iterations and got up to 12 kg more downforce at 180 km/h.

SPLITTER-V3-1-edit.jpg

SPLITTER-V3-2_EDIT.jpg

Cp+Streamline_edit.jpg

The design will keep evolving for aesthetic reasons and to try and extract more aerodynamic performance out of it. Next up is the first simulation of the canards. I would be great if you could share your feedback, experiences and thoughts! :thumbsup:

For those who are interested a few more details are available in the thread I started on ZPOST: http://www.zpost.com/forums/showthread.php?t=1484233
 
Interesting.
What did you use to create the zed mesh?
And which CFD software did you use and did you take different air-densities/temps into account?
I've used ANSYS CFD for modelling hydrodynamics on ship hull designs and specifically for thruster nacelles and pods. Takes hours to simulate for different climates / sea conditions! Even using distributed computing. :o
 
Awesome stuff! As an engineer it's great to see someone taking such a thorough approach to the topic!

What's the limit of added downforce that can be reached just with the addition of relatively subtle (relative to something like a giant wing on the boot!) parts like these?
 
Nice stuff!
My hands-on approach resulted in this spoiler, which together with the Eibach springs made the front end a LOT more stable at 260km/h on Autobahn etc.

So much that I actually had to come up with a stabilizer bar in the middle of the floorpan, because after every speed run it had buckled down! (I suppose from the downforce generated.) So that I think will be your next mod too! :)
(2 small holes & a long ziptie to the fan chassies would work too obviously)

638CA41A-FB5A-4589-8398-075E954F31A9.jpeg
 
Chris_D said:
Interesting.
What did you use to create the zed mesh?
And which CFD software did you use and did you take different air-densities/temps into account?
I've used ANSYS CFD for modelling hydrodynamics on ship hull designs and specifically for thruster nacelles and pods. Takes hours to simulate for different climates / sea conditions! Even using distributed computing. :o
Click to expand...

Thanks for the reply Chrid_D! Sounds like some interesting projects. Where the hull simulations multiphase?

I am using open source software for all of the simulation work. Because my simulation is below Mach 0.3 the compressibility effects are generally negligible. However, there are obviously various heat sources and heat exchangers which have an influence on the surrounding flow. Based on the flow paths and the parts of interest being either quite far away from this flow or upstream I have made the appropriate efficiency trade-offs. The simulation already takes a good day to solve with this in place! :lol:

Mangozac said:
Awesome stuff! As an engineer it's great to see someone taking such a thorough approach to the topic!

What's the limit of added downforce that can be reached just with the addition of relatively subtle (relative to something like a giant wing on the boot!) parts like these?
Click to expand...

Thanks for your reply Mangozac! Good question and not an easy one. Based on the initial runs, the local improvements I anticipate the final version to have a few dozen kg’s of downforce from the splitter and canards. I found some data on commercially available universal RW’s. At moderate angle of attack the mid-range option is said to make around 120 kg scaled to the speed I am testing at. When the whole underfloor is designed correctly it can easily outperform such a wing in terms of raw downforce but also efficiency (downforce vs drag.)

Thanks everyone else for the replies! I thought I get some GULF inspired colours out there on the options :thumbsup: Are any of you guys running aero bits on your Z4? Looking good Argenta, what material did you make it from?
 
Thanx! Its rubber, generic ebay spoiler rubber profile that’s been cut/sanded to fit.

I look forward to your final product!
 
I managed to run the simulation of the first draft canard. I positioned and shaped it to complement the lower line of the side ducts.

Canard-Start-V1-edit.jpg

Aerodynamically it is doing what it is supposed to. It raises the static pressure on the top surface and increases the suction underneath. This pressure difference yields the formation of a vortex which when working correctly will help manage the wheel wake. Unfortunately although aerofoil shaped, the suction on this first canard iteration is very peaky and too much on the nose of the element. The by-product is that the vortex health is suboptimal and dissipates too quickly.

Streamlines-edit.jpg

There are some good opportunities to improve the aerodynamic properties drastically by redistributing the pressure and managing the vortex strength. This will benefit the local performance and downstream influence.

What do you guys think? More to come! 8)
 
I have no comments of value to provide, but I'm really enjoying seeing this process so please continue to share!
 
Having briefly been involved with some wind tunnel tests a few years back, I’ve become very skeptical of any ‘aero’ mods performed by most enthusiasts, so seeing this kind of work being performed on our platform really is great to see :thumbsup:

Do you plan to do any work on the side ducts that vent in to the wheel arch or plan to experiment with other areas of the body?

Also,I don’t suppose you scanned the underside of the car by any chance? Would the scan data be useful enough for simulations?
 
Mangozac said:
I have no comments of value to provide, but I'm really enjoying seeing this process so please continue to share!
Click to expand...

Thanks Mangozac. I will continue to share updates so please do chime in!

MrPT said:
There has been a nice influx of talented b*stards recently. :thumbsup: :D
Click to expand...

Hehehe I try :lol:

beanie said:
Having briefly been involved with some wind tunnel tests a few years back, I’ve become very skeptical of any ‘aero’ mods performed by most enthusiasts, so seeing this kind of work being performed on our platform really is great to see :thumbsup:

Do you plan to do any work on the side ducts that vent in to the wheel arch or plan to experiment with other areas of the body?

Also,I don’t suppose you scanned the underside of the car by any chance? Would the scan data be useful enough for simulations?
Click to expand...

Any interesting wind tunnel tests if you don't mind sharing? :D At the moment I don't have any work planned for the side ducts themselves. The mass flow through the side ducts did increase with the first canard iteration. It will be interesting to see how this evolves as I keep refining the designs.

During the reverse engineering we managed to capture the larger underside details. I have ommited all the nitty gritty like bolts and fixings in the interest of simulation turn around.

Long term I would like to design and develop some components for other areas as well. The aim is to create a bit of a performance package. :thumbsup:
 
Sadly there's nothing of any particular interest really, at least nothing as exciting as working on a supercar or lemans racer! We were doing early testing on a full size model of a medium SUV to try and reduce its drag-this amounted to nothing more than screwing on a few bits of aluminium as makeshift lower air dams and sticking on a few bits of aluminium tape here and there! :D I can't remember the numbers now but I seem to remember making decent gains with it and it not fairing too badly. Simulation work carried on for a while after but unfortunately the project was canned before things got anywhere near production. Was a good learning experience though and really opened my eyes to how even just small changes can have quite a large cumulative effect.

It's great that you got so much information to work with, I'm sure there are plenty of track junkies out there, across all marques, that would happily pay for a thoroughly engineered aero package 8) I'm really looking forward to seeing where you go with this :)
 
I remember reading that the Z4MC generates quite a lot of rear lift. The cockpit is set very far back, so the airflow doesn’t stick to the rear window very well, and there isn’t really any underbody area to use to generate aerodynamic grip unless you heavily modify the exhaust and/or extend the floor illegally. Not an issue for most of us, thankfully!
 
MrPT said:
I remember reading that the Z4MC generates quite a lot of rear lift. The cockpit is set very far back, so the airflow doesn’t stick to the rear window very well, and there isn’t really any underbody area to use to generate aerodynamic grip unless you heavily modify the exhaust and/or extend the floor illegally. Not an issue for most of us, thankfully!
Click to expand...
You could fit a rear gurney flap, ducktail spoiler, or GT wing.

There are also rear diffusers/undergraysto smooth the flow from the rear. I think there was an OE one, a FancyWide aluminium version, and Goke/Slek/Varis carbon ones were all available at one time or another.
 
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