Implementation of Vortex generators on Underbody downforce

Hello,

I am new to the Forums but not new to FSAE. Our team is attempting to make the jump to making our first ever full aero package with wings and an under tray in school history. We are a low budget, very low member count team, making this task quite a workload for those involved.
The aero package is being implemented on an existing car that was never designed for aero, so I am running into issues with flow reversal on the exit of the diffuser, as the current suspension set up impedes the use of a large low angle exit ramp, leaving us only the option of running a short high angle diffuser (11-14 degrees) I have been investigating the use of vortex generators
as a means to improve the under body flow and reduce flow reversal, back into the diffuser. While I understand that flow must have turbulence induced upon it to delay flow separation, I have yet to be able to find any data or on distances from the diffuser ramp to the vortex generators and where they should be positioned. I am using Star CCM at 35mph-50 mph, and have yet to see any real benefits through several varying designs. While I know we could probably see better results with lower exit angles and using venturi tunnels, we are not in a position to design and manufacture ultra complex under trays. We are working on a one 1/8" aluminum sheet kind of budget, not a carbon fiber mold cast work of art budget.

Our team is interested in hearing from other teams or anyone with experience with under body flow on where and how to implement and design vortex generator to improve diffuser exit flow. If anyone has any experience with this, please feel free to contact me here. Thanks!



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