Characterization of a High-Frequency Pulsed-Plasma Jet Actuator for Supersonic Flow Control

Abstract

An experimental study is conducted to characterize the performance of a pulsed-plasma jet (called a "spark jet" by other researchers) for potential use in supersonic flow control applications. A pulsed-plasma jet is a high-speed synthetic jet that is generated by striking an electrical discharge in a small cavity. The gas in the cavity pressurizes owing to the heating and is allowed to escape through a small orifice. To obtain an estimate of the relative strength of the pulsed-plasma jet, the jet is injected normally into a Mach 3 crossflow and the penetration distance is measured by using schlieren imaging. These measurements show that the jet penetrates 1.5 boundary-layer thicknesses into the crossflow and the jet-to-crossflow momentum flux ratio is estimated to be 0.6. A series of experiments was conducted to determine the characteristics of the pulsed-plasma jet issuing into stagnant air at a pressure of 35 torr. These results show that typical jet velocities of about 250 m=s can be induced with discharge energies of about 30 mJ per jet. Furthermore, the maximum pulsing frequency was found to be about 5 kHz, because above this frequency the jet begins to misfire. The misfiring appears to be due to the finite time it takes for the cavity to be recharged with ambient air between discharge pulses. The velocity at the exit of the jet is found to be primarily dependent on the discharge current and independent of other discharge parameters such as cavity volume and orifice diameter. Temperature measurements are made using optical emission spectroscopy and reveal the presence of considerable nonequilibrium between rotational and vibrational modes. The gas heating efficiency was found to be 10% and this parameter is shown to have a direct effect on the plasma jet velocity. These results indicate that the pulsed-plasma jet creates a sufficiently strong flow perturbation that holds great promise as a supersonic flow actuator.Nomenclature j = density of the pulsed-plasma jet 1 = freestream density u j = exit velocity of the pulsed-plasma jet u 1 = freestream velocity

Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator

“…This actuator is able to produce high-speed jet velocities, with a peak velocity measured by the PIV technique in excess of 50 m/s [13]. A pulsed plasma jet inspired by the sparkjet actuator is presented in [14], with a jet velocity of the order of 300 m/s. The ONERA, in collaboration with the CNRS Laplace laboratory (France), is also involved in research into a PSJ actuator [15].…”

“…In recent years, various studies have been conducted on electrostatic and electromagnetic actuators. Actuators making use of piezoelectric materials [1][2][3] or plasma [4][5][6][7][8][9][10][11][12][13][14][15] are also being developed. There are several possible configurations for piezoelectric actuators, including: a synthetic jet [1][2] and a flat plat actuator [3].…”

Joule heating flow control methods for high-speed flows

“…Narayanaswamy et al 83 also observed that there is a limit on the frequency used due to the actuator beginning to miss pulses at higher values. The geometric features examined by Sary et al 80 were the neck radius i.e.…”

“…It has been noted that, with continuous use, increasing temperatures can slow the refill time of the actuator cavity and thus place an upper limit on the operating frequency. 80,83 Depending on the scenario, higher frequencies may be a necessity for future applications e.g. position control of oscillating shock waves in high speed intakes.…”

Effect of the duty cycle on the spark-plug plasma synthetic jet actuator

“…Explanations of these steps will be comprehensively explained in the section 2. Narayanaswamy et al [6] carried out the experimental study via PSJ actuator having different cavity volume and orifice diameter. They had measured temperature of actuator by using optical emission spectroscopy and also obtained jet exit velocity of about 250 m/s with consuming discharge energies of about 35 mJ per generated jet.…”