Characterisation of plasma synthetic jet actuators in quiescent flow

Abstract

An experimental characterisation study of a large-volume three-electrode Plasma Synthetic Jet Actuator (PSJA) is presented. A sequential discharge power supply system is used to activate the PSJA. Phase-locked planar Particle Image Velocimetry (PIV) and time-resolved Schlieren imaging are used to characterise the evolution of the induced flow field in quiescent flow conditions. The effect of orifice diameter is investigated. Results indicate three distinct features of the actuator-induced flow field. These are the initial shock waves, the high speed jet and vortex rings. Two types of shock waves with varied intensities, namely a strong shock wave and a weak shock wave, are issued from the orifice shortly after the ignition of the discharge.. Subsequently, emission of a high speed jet is observed, reaching velocities up to 130 m/s. Pronounced oscillation of the exit velocity is caused by the periodical behaviour of capacitive discharge, which also lead to the formation of vortex ring trains. Orifice diameter has no influence on the jet acceleration stage and the peak exit velocity. However, a large orifice diameter results in a rapid decline of exit velocity and thus a short jet duration time. Vortex ring propagation velocities are measured at peak values ranging from 55 m/s to 70 m/s. In the case of 3 mm orifice diameter, trajectory of the vortex ring severely deviates from the actuator axis of symmetry. The development of this asymmetry in the flow field is attributed to asymmetry in the electrode configuration.

Effect of slotted exit orifice on performance of plasma synthetic jet actuator

“…Here, the two-dimensional Euclidean sum of the measured velocity components is denoted as in the xz plane and in the yz plane, where U x , U y and U z and are the components of velocity in the three coordinate directions. Extensive analysis of the phase-averaged velocity fields pertaining to the round orifice shape is available in (Zong and Kotsonis 2016). Thus, the following section concentrates mainly on the slot orifice actuator and the differences of the latter to the round orifice actuator.…”

Electro-mechanical efficiency of plasma synthetic jet actuator driven by capacitive discharge

“…Centre of the jet exit is set as the origin of the coordinate system. Configuration of the power supply is described in detail in Zong & Kotsonis [9], thus not repeated here. Five cases are investigated, as listed in Table 1.…”

“…2, are measured by a high-voltage probe (LeCroy, PPE20kV) and current monitor (Pearson, Model 325), and recorded by an oscilloscope (Tektronix, TDS 3054C). Details on the discharge circuit are available in Zong & Kotsonis [9]. With discharge current chosen as the state variable, the mathematical model of discharge circuit (RLC series circuit) can be simplified as a second-order differential equation [10].…”

“…By placing an interrogation window directly over the jet exit, change of spatially-averaged exit velocity can be monitored. A detailed description of the PIV setup and the used interrogation window can be found in Zong & Kotsonis [9]. The variation of exit velocity is shown in Fig.…”

Interaction between plasma synthetic jet and subsonic turbulent boundary layer

“…In contrast to the steady jets, plasma synthetic jets demonstrate a highly dynamic behaviour. The jet exit velocity of the PSJA changes dramatically in one period (Zong & Kotsonis 2016a). As a result, the major flow structures produced by the interaction between PSJ and crossflow may exhibit strong spatiotemporal behaviours.…”