The Fraunhofer ENAS develops various fluidic actuators for the active flow control. Therefore performance requirements of the partners are considered on the one hand and new concepts are developed on the other hand to make the actuators more compact, efficient and capable of being integrated. During the development two different streams are pursued: on one hand actuators without compressed air supply, which are called Synthetic Jet Actuators (SJA), and on the other hand actors, which switch the compressed-air systematically, so-called Pulsed Jet Actuators (PJA).
In the aviation industry Synthetic Jet Actuators (SJA) are known for some years for Active Flow Control (AFC). A Synthetic Jet Actuator is a resonant electro-acoustic / electro-fluidic drive in a compact design with low power consumption. At an effectively net zero mass flow it generates a pulse greater than zero. Important characteristics of the actuators are the resonance frequency, the exit velocity and the flow of volume or mass. These are strongly dependent on the geometrical dimensions of the system. To optimize the SJAs for specific applications, it is necessary to completely describe the actuators. According to a SJA concept, which was newly developed by Fraunhofer ENAS, and in contrast to the conventional SJAs, a Helmholtz resonator is equipped with two membrane converters that are attached to its side walls to increase the efficiency of the actuators. For this construction new models need to be developed for the optimization.
Pulsed Jet Actuators
In contrast to most of the known systems the Fraunhofer ENAS takes the approach to use micro fabricated valves to switch the flow. These are directly integrated into an optimized chamber and controlled by sensors.