Qualitative assessment of 3D flows using a flow visualisation technique

A three-dimensional flow visualisation technique has been developed and used to measure the three mean velocity components, the associated turbulence levels and the kinetic energy of turbulence. The experiment involved an inclined 45° circular jet in a rectangular enclosure. The technique makes use of three light sheets of different colour and a standard CCD colour camera interfaced to a video recorder and a PC. The analysis algorithm relies on determining the length and colour of the resulting tri-colour streaklines to provide rapid, field-wide, qualitative and quantitative velocity information which is not subject to ambiguity stemming from varying particle concentration fields. Characteristic results show good agreement with 3D-PIV data. The purpose of the experiment was the calibration of the technique rather than the study of the flow, hence the results reported should only be considered as an indicative for the study of the jet flow.