Flow Physics of a Pulsed Microjet Actuator for High-Speed Flow Control
Uzun, A., Soloman, J.T., Foster, C.H., and Hussaini, M.Y.
Flow control actuators based on a small-diameter source jet and a cylindrical cavity structure take advantage of the flow resonance within the cylindrical cavity to generate a variable-frequency, pulsed high-momentum microjet issuing through the cavity orifice. The flow-acoustic coupling, which leads to resonance within the cavity of the actuator, is the main driving mechanism behind the pulsed microjet. In the present study, a computational methodology based on high-order numerical techniques is used to simulate a highly unsteady and compressible pulsed actuator flowfield. Simulation generated flowfield results are analyzed to further understand the complex flow physics governing the pulsed actuator operation. The simulation provides significant details about the highly unsteady and complex microscale actuator flowfield, which are not observable from the experiments. Qualitative comparisons made between the simulated flowfield visualizations and the experimental microschlieren images show a reasonable level of agreement. We perform a dynamic mode decomposition to identify the dynamically important modes of the actuator flowfield. The additional insight gained into the flow physics through the simulation is useful in the design of more efficient and geometrically complex pulsed actuators for a range of high-speed flow and noise control applications.