Modeling Acoustic/Structural Interaction of Synthetic Jet Actuators

A new model is proposed to capture the interaction between the acoustic waves and the membrane vibration in synthetic jet actuators (SJA). Synthetic jet actuators are a class of actuators recently developed for active flow control. They usually contain a structure membrane as the vibrating resource, a cavity as the resonator, and an orifice for jet output. The vibrating membrane is used to create pressure fluctuations, which then propagate, bounce and resonate (under certain conditions) inside the walls of the cavity, and thus produce an oscillating jet through the orifice. The proposed modeling approach is to solve a 1-D acoustic equation with the vibrating membrane as one of the boundaries and the orifice for jet output as another. This approach results in a state-space model, which will not only help make synthetic jet actuators operate away from the structural resonance of the membrane (and thus extend the life of synthetic jet actuators), but also provide a convenient way of designing and optimizing multi-input, multi-output control systems required by many complex fluid flow systems. After validation with experiments, the model is used in an example of design optimization.