Dynamics of Fluidic Oscillators and Their Synchronization for Active Flow Control
Résumé
A series of new bi-stable fluidic oscillators which can generate discrete pulsed jets in a wide frequency range (50-300Hz) with maximum velocities of the order of 200 m/s has been developed for flow separation control purposes. A preliminary experimental analysis of the prototypes has been performed and the results have shown that the oscillation frequency has a nearly linear relationship with the length of its feedback loops. Thus, a new function is proposed to estimate the oscillation frequency according to the experimental results. In addition, numerical simulations are carried out in order to better understand the jet switching mechanism inside the oscillator and identify the parameters controlling the dynamics of these oscillations. Then, it is verified that the switching process of the internal jet is not only controlled by the pressure difference between the two control ports, but also by the pressure difference between the two main branches of the oscillator. Finally, two methods of synchronizing the oscillators are proposed and verified both experimentally and numerically. These new finds will be of great help in future design of this kind of fluidic oscillators and their applications in active flow control of separated flows.