Turbulent mixing in free swirling jets

A light scatter technique, marker nephelometry, was used to study the nozzle fluid concentration field of free swirling turbulent jets. Swirl was generated by guide vanes in a 7.14 cm diameter nozzle giving swirl numbers of 0.385, 0.667, 1.16 and 1.43. The parameters measured include those describing the self preserving forms of the mean concentration field, the intensity and integral scale of the concentration fluctuations, and the intermittency for the jets without internal recirculation (swirl number less than 0.7). Results show that swirling jets without internal recirculation are very similar in structure. The data for the two jets with internal recirculation zones are given as contour maps describing the mean concentration and fluctuation intensity fields. The results as a whole describe jets with weak to moderate swirl and indicate the trends to be expected for jets with strong swirl.