Experimental investigation of opposed rectangular impinging jets confined in an open cavity with vertical crossflow in a rectangular duct

An experimental investigation is carried out using stereoscopic time-resolved particle image velocimetry (TR-PIV) to study the dynamics of the flow structure of two turbulent planar water jets impinging normally against each other inside an open cubical cavity subjected to external lateral flow. The cavity depth is equal to the channel depth and both jets and the crossflow are kept at ambient temperature T₀. The three-dimensional near field flow development has been investigated for fixed nozzle separation at crossflow Reynolds number defined with the channel hydraulic diameter of 3000 for three jets’ Reynolds numbers based on the inlet velocities and nozzle hydraulic diameter ranging from 1500 to 5000. In this arrangement, the jet impingement moves off center, the flow fields are asymmetric with respect to the cavity mid-span and exhibit self-sustained oscillations with a pronounced three-dimensional flapping motion. Based on the measured data in planes normal to the cavity floor, mean and instantaneous velocity and vorticity distributions and turbulent statistics have been analyzed and characterized. In addition, spectral analysis of the oscillating instability is performed to analyze the effects of the confinement boundaries and the interactions between the jets and the crossflow on the spatio-temporal dynamics of the flapping flow and the oscillatory motion of the vortex structures.