Book Description

This report presents the results of two experimental activities. Part I involves passive control of mixing and noise in a rectangular supersonic jet. Part II involves development and characterization of high amplitude and high bandwidth actuators for use in active control of high Reynolds and Mach numbers flows such as the jet in Part I. Nozzle trailing edge modifications were used in part I, which substantially enhanced mixing and reduced noise radiation in non-ideally expanded conditions, but did not significantly alter the mixing or noise for the ideally expanded flow condition. In part II, an in depth investigation of the Hartmann Tube was carried out. The effects of tube depth, separation distance between the tube and the nozzle, and the jet Mach number were explored. Experiments were also performed on a Hartmann Tube based Fluidic Actuator. Striking similarities were observed in the frequency content and amplitude of tonal frequencies in the global near-field pressure and far-field acoustic measurements, as well as, the flow results. Time traces of pressure in the tube were used to explain the major differences between the primary frequency of HT and the quarter-wave frequency. Flow visualization results showed a pulsating flow very rich in vortical structures.