Design and Characterization of High-Bandwidth, Resonance Enhanced Pulsed Microactuators: A Parametric Study

An extensive study on a microactuator that can generate high-momentum, high-frequency perturbations over a large bandwidth is presented in this paper. Such an actuator can potentially be used for the active control of various shear and boundary-layer flows that involve separation, mixing, and noise generation. The resonance enhanced microjet actuator described in this paper is a simple microfluidic system consisting of an underexpanded source jet flowing into a specially configured cavity integrated with multiple micronozzles, through which unsteady pulsed supersonic jets issue. The resonance frequency of these microjets could be varied over a large range (approximately 1-60 kHz) by changing the geometric and flow parameters of the microactuator system. Mean and unsteady properties of the microactuator are examined, including time-resolved flow visualizations and synchronous pressure and noise measurements; collectively, they provide a better understanding of the actuator dynamics. The present study also explores the design space and performance, as well as some of the design limitations of this actuator. Based on this parametric, a correlation is suggested that may be used for designing such actuators for various applications.