Fluid-Structure Interaction Model for Low-Frequency Synthetic Jets

Advancements in microelectronics have increased circuit board heat densities to the point where active cooling is required. Synthetic jets offer interesting capabilities for localized active cooling of electronics due to their compact size, low cost, and substantial cooling effectiveness. The design of synthetic jets for specific applications requires practical design tools that capture the strong fluid - structure interaction without computationally long run times. There is particular interest in synthetic jets that have a low operating frequency to reduce noise levels. This paper describes how common finite elements and codes can be used to calculate parameters for a synthetic jet fluid - structure interaction model that only requires a limited number of degrees of freedom and is solved using a direct approach for low-frequency synthetic jets. Extensive tests are performed with the synthetic jet in vacuum to measure deflection, in ambient air to measure pressure and exit velocity, and impinging on a heated surface to measure heat transfer enhancement. The test results are compared with the fluid - structure interaction model results for validation, and agreement is found to be good in the frequency range of interest from 200 to 500 Hz. [PUBLICATION ABSTRACT]