Active control of supersonic impingement tones using steady and pulsed microjets

Aeroacoustic resonance and self-excitation in screeching and impinging supersonic jets – A review

“…161 Proper orthogonal decomposition (POD) remains the most widely used decomposition method in fluid mechanics, 184,185 and this is equally true for flow resonance. Applications of POD to resonant flows include screeching axisymmetric jets, 23,33,34 screeching rectangular jets, 55,57 screeching elliptical jets, 68,186 jets from multi-stream nozzles, 187 jets impinging on both planar 105,188 and curved 102,103 surfaces, twin-jet systems, 38 and many others. The highly periodic nature of resonant flows makes them particularly amenable to POD, as it is typically possible to reconstruct the entire resonance cycle from only the leading POD modes.…”

Fundamentals and Applications of Modern Flow Control

“…Pulsed jets thus require an external fl ow source, and the jet fl ow can be modulated using, for example, a fast-acting solenoid valve , a highspeed siren valve (Williams et al, 2006b), or a rotating orifi ce/slot assembly (Choi et al, 2006). It is important to note that it is not possible to phase-lock the latter two (rotary) types of pulsed jets with a reference signal in the fl ow because of limited time response.…”

Control of air micro-jets by the use of dielectric barrier discharges

“…Their study and use have become more and more popular because of their great potential for flow control, especially control of separated flows. The pulsed micro-jets are a new and promising type of actuator which have been developed as an extension of the stationary micro-jets used for the control of external flow separation [1,2] and for active control of supersonic impingement tones in [3]. Synthetic Micro-jets have been also successfully developed for aerodynamic flow control in [4].…”