Active flow control for high speed jets with large window PIV

The current work investigates a Mach 0.6 jet flow field with particle image velocimetry (PIV) and simultaneously sampled near and far-field pressure. Two component velocity measurements are taken in the streamwise plane of the jet. Three cameras are placed such that each interrogation window is captured simultaneously and stitched together to obtain a six diameter PIV window. In addition, active flow control is applied using an actuation glove comprised of synthetic jet actuators. Both open and closed-loop control are applied in different physical forcing configurations. For closed-loop control, hydrodynamic pressure from the near-field array of sensors is fed back to the actuation system in real time. The large window PIV allows one to examine how the flow field is affected by the flow control. Low-dimensional modeling techniques, in the form of proper orthogonal decomposition, are performed in order to obtain a better understanding of the large scale, energetic events in the flow field. It has been found that active flow control changes the potential core length and shear layer expansion, which affects the overall sound pressure levels in the far-field.