A semi-quantitative flow visualisation technique, based on laser-induced fluorescence in water, was used to characterise the mixing which occurs when a precessing jet and a central axial shaping jet interact. The momentum ratio between the central axial jet and the precessing jet was found to be the controlling parameter in determining the growth rate and structure of the combined jet flow field. For all ratios, the results demonstrate that the two jets interact strongly, generating large coherent structures which span the entire width of the flow from the exit plane. The spreading angle and hence the size of the large-scale structures of the combined jets was found to depend directly upon the momentum ratio.
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