Investigation of micro-jet active control of a precessing jet using PIV

A circular jet entering an open-ended concentric circular chamber can rotate or precess about the jet axis for certain flow conditions and chamber configurations. Active flow control of a precessing jet provides the ability to influence the flow field inside the chamber and the resulting flow after the chamber exit. Twelve micro-jets surrounding the jet at the chamber inlet are used as actuation. At the chamber exit, four pressure probes and three-component velocity measurement using stereo particle image velocimetry (stereo-PIV) is used to monitor the flow. A phase plane method using signals from the pressure sensors is developed to monitor the location of the jet high-velocity region in real-time. Phase-locked stereo-PIV, triggered by the micro-jet actuation signal, is used to investigate the flow field and validate the pressure phase plane results. The effectiveness of the micro-jet actuation and the validation of the pressure phase plane measurements demonstrate actuation and the sensing needed for future closed-loop control of the precessing jet.