Aerodynamic functions
Active aero wheels are right on the cutting edge. For decades, the automotive industry has been working on concepts to minimize the annoying air resistance, or drag coefficient (cd), on the fast-rotating wheel. This resistance accounts for a significant portion of the overall aerodynamic drag. It directly impacts vehicle efficiency and contributes to range anxiety in electric vehicles, especially battery electric vehicles (BEVs). The designs of newer electric vehicles show that, for reasons of efficiency and range extension, more closed wheel designs with smaller openings are becoming more popular. These designs are often complemented by air curtains. This combination can reduce air resistance by a few percentage points, but not more. Only fully closing the wheel can completely prevent the airflow and the harmful rotor effect of the wheel. However, this is in conflict with the required thermal management of the braking area. In situations such as mountain pass descents and emergency braking, the brakes become very hot, and this also applies to electric vehicles, as such braking power cannot be absorbed purely via recuperation.
CompActive's actuator modules now allow multiple ventilation flaps, part of an active aero system, to be integrated into the wheel. These flaps automatically open due to the heat from the braking system and initiate cooling through the wheel surface. Since they operate without a power source, they can be easily applied to the rotating parts. The flat bending actuators provide sufficient travel and the necessary robustness for an element that rotates quickly in road traffic.
Active vortex generators or adaptive turbulators resolve the contradiction between safe landing and efficient cruising flight. This has also been demonstrated by the flight tests that have already been carried out as part of a ZIM cooperation project by the partners Leibniz Institute for Composite Materials and DG Flugzeugbau. Adaptive vortex generators (VGs) can be used to improve the aerodynamic performance of almost any winged aircraft. Depending on the area of application, they offer the possibility of reducing the minimum flight speed or noise development on demand without compromising cruising efficiency. The boundary conditions of the application - a very limited installation space, the lowest possible weight and the realization of a large number of small actuators - make it difficult to realize this functionality with conventional mechanical systems. The Curve bending actuators with material-integrated actuators enable an actively controllable function even under such requirements. A single active vortex generator with a height of 1.8 mm and a weight of 1.5 g is able to generate a tip deflection of 17 mm.
With increasing efficiency requirements in aviation and especially when it comes to flying electrically or taking off with sustainable but expensive energy sources such as hydrogen (H2), all possibilities for maximum cruising efficiency must be exploited. This includes, for example, the use of so-called laminar wing profiles, which, however, are also known to react critically, especially on landing, thereby reducing safety levels. This conflict can be resolved by using active vortex generators. Similarly, flow control techniques can be used to reduce noise levels during takeoff and landing in urban areas. By implementing these adaptively with curve actuators, the aircraft can revert to efficient airflow during cruising altitude.
