Car makers are getting more serious about manipulating air flow through the vehicle, rather than just around it. We saw a good example of that with the new Aston Martin DB11, which was revealed at the Geneva motor show earlier this month.
On the rear of the GT supercar, the designers and engineers incorporated what they described as a “virtual spoiler.” This involved trunking air from intakes situated at the base of the C-pillars and running it under the bodywork to emerge vertically along the rear of the car.
Media reports suggest the “aeroblade” was the result of engineering designer, Marek Reichman, attempting to eliminate the rear wing for aesthetic reasons. Aston still wanted the downforce, however, so this was the solution.
The faster the car goes, the more air is pushed through the ducts and the more downforce is generated. Higher speeds trigger a small gurney flap to rise. Aston also vents air from the brand’s trademark strake behind the front wheel arches to lift the car slightly to help with steering tactility.
Right now, this practice of creating unconventional air channels through the bodywork is limited to higher end cars with more freedom on looks and usage of space. The Ford GT supercar with its buttresses on the rear quarter panels is another good example of this.
Optimizing a vehicle for better aerodynamic performance is not as simple as altering the exterior shape. Many constraints are placed on the vehicle shape including design, cooling airflow, occupant packaging, and manufacturing.
Because these constraints naturally conflict with the optimal aerodynamic solution, creative methods of manipulating downforce and drag may be required. Managing these multiple, competing constraints is becoming a bigger challenge in the automotive development process.
Presently, designing air channels through mass-market cars is hard with the current architectures, as there’s very little available space. But that could change with electric cars.
With EV-only platforms, makers can place batteries and motors almost wherever they please, so designers can turn their attention to aerodynamic drag reduction. That’s going to increase range and will help make EVs more viable, particularly on longer journeys. With the increased packaging freedom, additional variables will be introduced into the development process increasing the need for robust multi-variable optimization.
As with many other technologies, you saw it on supercars first.
Dr. Brad Duncan is an automotive aerodynamicist with a background in aerodynamic design, motorsports, wind-tunnel testing, computational fluid dynamics (CFD) and aeroacoustics. Specialties include aerodynamic drag of automobiles, aerodynamic lift of high-performance vehicles, motorsports and transient aerodynamics including spectral analysis and aeroacoustics.
