Noise Control of High Reynolds Number Mach 1.3 Heated Jet Using Plasma Actuators

Recently, heating capabilities have been added to the free jet facility at the Gas Dynamics and Turbulence Laboratory (GDTL) of Ohio State University using a storage-based off-line electric heater. This addition makes it possible to test the effectiveness of the localized arc filament plasma actuators (LAFPAs) for the purposes of noise mitigation and mixing enhancement over a wide range of temperatures. These actuators have been used successfully at GDTL in high Reynolds number, high-speed unheated jets. The facility consists of an axisymmetric jet of exit diameter 2.54 cm with different nozzle blocks and variable jet temperature in an anechoic chamber. The focus of this paper is on a high subsonic (Mj = 0.9) jet. Characterization of this jet with heating capabilities shows consistency with previously published results in far-field acoustic characteristics as well as centerline velocity and turbulent kinetic energy profiles. A total of sixteen combinations of forcing azimuthal modes (m = 0, 1, 3, and ±4) and temperature ratios (To/Ta = 1.0, 1.5, 2.0, and 2.5) at a wide range of forcing frequencies were collected to examine LAFPAs effectiveness for far-field noise mitigation. The results show that LAFPAs can consistently produce significant reductions in noise levels. Across the range of temperatures explored here, the effectiveness of LAFPAs improves as temperature increases. Possible reasons for the increase in effectiveness are discussed. D = jet exit diameter (m) Mj = jet Mach number Uj = jet exit velocity (m/s) m = azimuthal mode To = jet stagnation temperature (K) Ta = ambient temperature (K) StD = jet Strouhal number based on jet diameter StDF = forcing Strouhal number based on jet diameter SPL = sound pressure level (dB) OASPL = overall sound pressure level (dB) x = streamwise coordinate (m) y = normal coordinate (m) I.