Experimental study of oscillation of axisymmetric turbulent opposed jets with modulated airflow

Oscillation behaviors of axisymmetric opposed jets with modulated airflow were experimentally studied. The oscillation frequency, the oscillation amplitude, and the movement velocity of the impingement plane at various nozzle separations, excitation frequencies, and exit turbulence intensities have been investigated by a hot‐wire anemometer and flow visualization technique combined with a high‐speed camera. Results show that the oscillation frequency of the impingement plane is nearly equal to the excitation frequency, whereas the oscillation amplitude decreases with the increase of the excitation frequency. The full‐scale amplitude oscillation occurs at low excitation frequencies and 2 ≤ L/D ≤ 8 (where L is the nozzle separation and D is the diameter of the nozzle exit). With the increase of the exit turbulence intensity caused by a turbulence generating plate, the oscillation amplitude decreases remarkably. Flow regimes of axisymmetric opposed jets with excitations are analyzed and discussed based on the experimental results. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4828–4838, 2013