Investigation of synthetic jet actuator design parameters

The vital attention of this project is directed to active flow control over micro aerial vehicles using synthetic jet actuators. Previous research has demonstrated that oscillating micro-jets have the potential to influence the flow characteristics and change the aerodynamic performance of the airfoils.(1) The aspiration of this effort is to build on the previous work and support the idea of using synthetic jet actuators to improve the deteriorated aerodynamic characteristics of the low Reynolds number flow regimes and potentially use the same structure as a maneuvering device. The main idea is to actively control the pressure distribution over an aerodynamic surface which could lead to elimination of flow separation, lift increase and drag losses. To understand the efficiency of the synthetic jet actuators and the potential for such applications, it was necessary to investigate the nature and the variety of their performance with different design configurations. This paper covers the characterization of synthetic jets, starting with the analysis of different types of diaphragms, diverse size and shape cavities and different size and shape of the exit nozzles. The diaphragm with the thickness/diameter ratio of 0.17 made out of 0.01 inch thick brass shim was found to be the most effective of those studied. The volume and the shape of the cavity were related and it was noticed that the performance of the synthetic jet actuator increased when the device was tuned such that the resonant frequency of the diaphragm and that of the cavity were close to matching. A square diaphragm supplied better displacement characteristics than the circular diaphragms studied and also showed better results when integrated with the enclosed cavity forming the final device.