On the use of Plasma Synthetic Jets for the control of jet flow and noise

Abstract

The noise generated by an isothermal single stream jet at Mach number Mj = 0.9 and diameter-based Reynolds number ReD = 10 6 is investigated numerically for an unforced configuration and a forced configuration with an active control device. This active flow forcing is performed with 12 Plasma Synthetic Jets (PSJs) located at the nozzle lip and acting on the axisymmetric mode of the shear layer of the main jet with a forcing Strouhal number StF of 0.14. Simulated flow and noise results are validated with comparisons to available experiments performed for identical jet conditions. The noise radiation of the reference, unforced jet is globally well recovered numerically with a limited overestimation of the experimental pressure levels, below 3 dB for most of the observations angles. In the presence of the control, the simulated interaction between the fluid injected by the PSJs and the main flow reproduces very well the development of a large coherent vortex observed experimentally in the jet shear layer. The control is also found to favour the generation of turbulence. It translates for the acoustics to an increase of the broadband noise and of the integrated pressure levels of 1.5 dB in both experiments and simulations.

Modal analysis of jet near-field pressure fluctuation

“…Unfortunately, it does not coincide with the position of the linear antenna, but PSE computations will make possible some comparisons between both surfaces. A more detailed presentation of the unsteady simulations and associated results is available in (Huet, 2014).…”

Experimental and numerical response of a high-Reynolds-number M=0.6 jet to a Plasma Synthetic Jet actuator

“…Using a simplified model of the LAFPA actuator, considered as a simple thermal source term, satisfactory agreements with measurements were reported, allowing the authors to investigate further on the aerodynamic mechanisms at play. Based on a simplified phenomenological model of the PSJ actuator, Huet (2014) have recently investigated the effect of pulsed microjets on the flow field and on the noise radiated to the far field by a M ¼ 0:9 jet with Re D ¼ 10 6 . This numerical actuation, performed for low actuation Strouhal numbers, led to the generation of a large coherent vortex convected downstream, promoting the generation of turbulence and increasing the broadband far-field noise.…”