Development of a Novel Analytical Model for Liquid Synthetic Jets and Introduction of Their Application in Immersion Cooling Systems

A synthetic jet, generated near the orifice of a synthetic jet actuator, emerges from a cavity with a periodically actuated wall. The vortical structures produced by synthetic jet actuators, due to their effective mixing and boundary layer agitation capabilities, present potential for applications in a wide range of electronics cooling applications. One potential application can be the integration of synthetic jet actuators inside immersion cooling tanks where there is a lack of effective targeted flow control. The study of synthetic jets encompasses their generation, formation, and both near- and far-field flow behaviors. However, for liquid synthetic jets, there is a notable deficiency in research across published literature. The first step in designing and studying liquid synthetic jets should begin with an examination of their generation. While lumped element models offer considerable versatility for designing synthetic jet actuators, such models for liquid synthetic jet actuators are currently lacking. Therefore, this study aims to adapt fluid dynamic-based lumped element model of air based synthetic jets and extend it to liquid synthetic jets, addressing this gap in the field. Synthetic jet actuators working with Shell immersion cooling fluid and water are modelled and results are compared with three dimensional CFD simulations. Studied devices were able to generate SJs at velocities of 6.15 m/s for water, and 6.8 m/s for synthetic oil system. It was observed that Helmholtz frequency happens in liquid system however at significantly higher frequencies, in comparison to air synthetic jet actuators. Phase lag between diaphragm actuation and jet exit velocity is also observed at wall resonance frequency, a phenomenon which needs to be considered in future studies. It can be concluded that presented lumped element model is an excellent tool for designing and rapidly assessing liquid synthetic jet actuators in the development process. However, in order to accurately characterize their heat transfer capabilities, detailed CFD simulations with compressibility consideration and further experiments are required.