This design is for an aerodynamic drag reduction device. This device works by producing a small powerful vortex near the boundary layer of a vehicle's body. This then adds momentum to the boundary layer, allowing for the air to stay attached to a surface longer. This attached airflow, then flows in the air void at the rear of a vehicle, reducing the drag.
While this idea of using vortex generators to reduce drag has been explored before, the designs for these other devices have not been effective enough to be commonly used in the automotive industry. However, the design that we have developed has been able to be 2-3 times as effective as these other vortex generator designs.
Vortex generators are able to create a vortex, by having air rotate over a wall from a high pressure region to a low pressure region. Currently other designs for these devices, have a straight wall that has been angled in relation to the airflow to create this pressure difference. However, we discovered that by putting a curve in the wall, the pressure difference was significantly larger, creating a stronger vortex. This stronger vortex is what makes our design much more effective at reducing drag. This design also easily allows for the vortex generator to be scaled in size, so it can be optimized for a car and for larger vehicles, such as a semi trailer.
The drag reduction that is produced from this device is then translated into fuel savings for combustion vehicles, or longer travel distances for electric vehicles. This design is also easy to install, and can be retrofitted onto almost any vehicle. Because of the substantial fuel savings that this offers to consumers, the potential market for this is extremely large. However, we have determined that the biggest impact for this device is in the trucking industry, given the importance of fuel prices for this market.
We developed our design through road tests and a CFD wind tunnel simulation. In the CFD tests, we found that the drag on a sedan could be reduced by 20% and semi trailers by 15% at speeds between 50mph and 85mph. Approximately for every 10% reduced drag, the MPG of a vehicle increases by 7%. For correlating the CFD with true performance, we conducted several hours of road tests at 60mph and 80mph. In these road tests we found that the drag was reduced by 21-22% on a sedan style car.
For testing and prototype purposes, we have been able to produce this design with 3D printing techniques. However, for commercialization we will use injection molding to cheaply and quickly produce these vortex generators. We have estimated that the manufacturing cost of implementing this design on a vehicle would be less than $2.