Development and Characterization of Hartmann Tube Fluidic Actuators for High-Speed Flow Control

An in-depth investigation of the Hartmann tube (HT) was carried out to gain a better understanding of and the effects of various parameters on its output flow characteristics. The HT used in this work consisted of an underexpanded jet directed into a close-ended cylindrical tube of the same diameter. 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 an HT fluidic actuator (HTFA). The HTFA operates under the same principles as the HT, except a major portion of the area between the nozzle and tube is shielded off, so that it can be used as a pulsating injector for flow control. Dynamic pressure measurements in the near field and microphone measurements in the far field provided temporal and spectral data. Instantaneous and phase-averaged images of the flow were obtained to explore the nature of turbulence structures within the flow. Limited hot-wire measurements were performed to characterize the velocity fluctuations at the exit of the HTFA