Self-excited wire method for the control of turbulent mixing layers

Experimental study of a supersonic jet-mixing layer interaction

“…This set-up consists of a M ϭ1.37 supersonic jet surrounded by a subsonic entrained co-flow. Stagnation pressure and temperature for the main jet are respectively 3ϫ10 5 Pa and 260 K. The coflow velocity and stagnation temperature are 47 m/s and 290 K. The convective Mach number is M C ϭ0.55, and the convective velocity U C ϭ230 m/s. The supersonic jet has the same static pressure as the subsonic co flow.…”

“…Lateral test section walls comprise large windows such that visualizations or laser Doppler measurements can be easily performed. A 200ϫ10 5 Pa dry air tank supplies the main jet.…”

“…3 and 4. The CJ stagnation pressure is kept constant at 2.5ϫ10 5 Pa, which results in a velocity ratio U CJ /U 1 Ϸ0.89. The CJ nozzle is convergent, and its exit is sonic.…”

“…Additional experiments were performed to test these hypotheses. Instantaneous visualizations were performed, increasing the stagnation pressure of the CJ up to 10 ϫ10 5 Pa. Two representative instantaneous images for a CJ stagnation pressure of 10ϫ10 5 Pa are shown in Fig. 14. Since the CJ nozzle is convergent, it is strongly underexpanded for this regime.…”

“…The former cathegory includes resonance based devices, such as cavities, 3 impingement obstacles, 4 and self-exciting wires. 5 The cavity size, obstacles geometry and position, the wire diameter and tension are adjusted such that the associated frequency matches that of the main flow instability. Such devices are technologically simple and can achieve significant mixing enhancement.…”