Jump to content
SAU Community

Recommended Posts

UAS has recently begun using Computational Fluid Dynamics (CFD) software to aid us in designing elements of our aerodynamics package.

Unforunately time and cost constraints make a true to life simulation a difficut task to achieve, as ideally every component down to the smallest washer should be modeled into the software and then animated to garner accurate results.

STANDARD CAR

FULL CAR SIMULATION

The above two videos show the flow trajectories over the UAS Zed and a standard 300ZX respectively. Though the models are rough they are enough to indicate significant changes in aerodynamic downforce and drag. The figures in the above simulations showed the UAS Zed generated five times more downforce than the standard 300ZX at 200km/h.

To give the exact measurements that is an increase from approximately 50kg to almost 280kg. Drag also increased but only by a factor of two with the standard car measuring 100kg of downforce to the UAS car's 230kg.

The UAS rear wing is a fantastic example of how we use the software to aid our design despite our time constraints. By focusing on a small area in isolation, we can more clearly judge how changes will impact our drag and downforce characteristics.

REAR WING

In this instance it was found that adding a 15mm gurney strip to the larger lower rear wing increased the overall downforce by a significant amount ( ≈ 11%). This produces an extra 14kg of effective weight on the rear at 200kph, with only ≈3% increase in total rear wing drag.

We have also been able to generate numerical data using the program. Doing so allowed us to find a number of interesting results.

On straights, the wear wing of the UAS Zed has a tendancy to flex under the downforce load. This change in area has an impact on the overall downforce of the wing.

circuit_battle.jpg

Using CFD analysis we were able to simulate a number of different instances. We simulated a straight wing, one with the top wing flexing to touch the lower and an instance of both flexing to the same degree. We did this at both 200km/h and 100km/h simulating a worst case scenario through high and low speed corners.

As can be seen from the tabulated data this flexing causes a drastic change in the dynamics of the wing. Both downforce and drag are significantly reduced as the wing starts to bend.

graph.jpg

On straights this is beneficial as it has the same effect as the adjustable rear wing systems used in the 2011 formula 1 season, if to a lesser degree, reducing drag so we can achieve a higher top speed.

In low speed areas it is slightly more detrimental, however it should be noted that at these speeds overall downforce is significantly lower and as such flex is reduced causing a corresponding reduction in overall downforce lost.

  • 4 weeks later...
  • 1 month later...
  • 2 weeks later...

what is the wing made of/? that is some serious flex

Carbon fibre epoxy resin with sandwich foam core. It flexes because it has 200+kg downforce.

We recently added an aluminium right angle gurney strip to the trailing edge of the main rear wing blade. This will stiffen it up a little bit, although the flex is not all bad as it creates maximum efficiency at low speed where it needs it most. At high speed as it bends it reduces efficiency but also less drag.

  • 1 month later...
  • 2 months later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Was there ever a model of the Stagea m35 that didnt have a badge on the grill? I thought I saw that somewhere, some aero edition or something? I cant find it again? davemoto
    • Its a 2002 vr-x four VQ25DET, silver. Coil overs, lowered, polished alloys and sport exhaust. Bit of a project, was sitting in a shed for a while but runs and drives great.
    • I wasn’t able to replicate the sound anymore. It was a one time sound so maybe it was just coincidence but it was like small pebbles being dropped in a coke can.   should I try cleaning the MAF? It could be it’s functioning but dirty? I don’t know.
    • Update 4: Hi all. The car drives again! Haven't driven for long, only to store it in the garage again, but the test drive was successful. The coolant and oil leaks seem to be fixed for now. Temps on the engine were also very good, while moving I never even saw 80C water during the approx. 30 minute drive. Ate up all the coolant in the reservoir though so will have to fill that even more when I go to the car next time. One thing that pisses me off is that the RPM gauge is still f**ked, I even resoldered the board twice and used copper paste on the silly screws that are used as connections. Next time I take it out I'll take apart the board and fit new components, I'll see if I can get a replacement IC for it.  I have an appointment set for 22nd of September for the engine tune to 370hp. Alignment also still needs to be done. My hope is that I can get all the legal stuff over with by the end of this season. Anyone of you have advice regarding intercoolers? Currently there is an APEXI core fitted, one of those weird hybrid ones, 600x270x76. I don't think it's bad but it's not new and now I still have the chance to change it now to legally include it in the paperwork. Only issue is that the only options that would arrive in time are a HKS Type R intercooler or generic Ebay spec intercoolers comparable to a JustJap one. Ideally I'd order a Plazmaman but it takes over a month to receive which would mean making the car legal has to wait until next season. Would love to hear some input on this. Same story for my injectors, the previous owner was a nunce and put ID 1050x on the engine. They work but are obviously not ideal at "normal" power levels. But I don't see a reason to change them unless the tuner says it's necessary. I read online before buying a different exhaust that the top secret style rear diffusers won't fit due to the size of the rear resonators. My buddy and I made it work by slightly "adjusting the shape" of the mounting bracket and making some spacers out of 3d print for the mounting bolts. Fits like a charm. Just putting this here in case someone has this problem. Even the hefty HKS Silent Hi Power rear can fits without hitting anything.
    • Well they got my money but they are not getting my gearbox ! 
×
×
  • Create New...