Exploring High-Speed Axisymmetric Jet Noise Control Using Hartmann Tube Fluidic Actuators

This work is part of an ongoing effort to better understand the influence of frequency and amplitude when controlling high Reynolds number, high-speed jets using a Hartmann Tube Fluidic Actuator (HTFA). In addition to HTFA forcing, a steady mass injector (SMI) with the same mass flow rate as the HTFA was used. Forcing was applied with two actuators separated by 180° and four actuators separated by 90° in the azimuthal direction. The jet under study was axisymmetric with Mach numbers between 0.6 and 0.98 and Reynolds number between 5.7 x 10 5 and 7.6 x 10 5 . To understand the influence of forcing on far-field noise, acoustic measurements were acquired at 30° and 60° with reference to the jet axis. With two actuators, the jet noise increased when the actuators operated at a frequency between St D = 0.2 - 0.5. Forcing with two or four actuators at higher Strouhal numbers (St D > 0.75) or with steady mass injection slightly reduced the peak broadband jet noise and increased the high frequency noise. The slight reduction was only observed when the total mass injection was greater than 1%. The actuators (SMI or HTFA) had their largest impact when they were injected at an angle between 45 and 60° with respect to the jet axis.