A Flow Study of Pulsed Jet Cross-Flow Interaction by Micro Particle Image Velocimetry

Recent development of micro devices is remarkable as in the examples of Micro-TAS, Lab-on-a-chip or ultra micro gas turbine. In order to make the micro devices smaller and more effective, an appropriate use of a micro scale jet as an actuator can be a key technology. Aiming at the development of a measurement system of the micro flow control devices in the future micro aerodynamics, we have established a system to measure a continuous jet, a pulsed jet and a synthetic jet for the flow control in the low Reynolds number air flow with a micro length scale. The two-dimensional flow field around the micro jet using micro particle image velocimetry (PIV) was measured. The jet was injected through the device using an acoustic speaker. It was observed that a saddle point existed at the certain phase where the velocity is 0 at the boundary of the jet blowing and suction phase for the synthetic jet into a still air. It was found that the pulsed jet and the synthetic jet are more effective in the fluid mixing in the low Reynolds number flow than the continuous jet. The dead water region was observed downstream of the jet in case of the jet injection into cross flow. It was recognized that the synthetic jet at the certain oscillation frequency generated a vortex pair near the jet hole.