Influence of a secondary, parallel, low Reynolds number, round jet on a turbulent axisymmetric jet

The influence of a secondary, parallel, low Reynolds number, round jet on the development of a turbulent axisymmetric jet with Re 5500 is studied experimentally by means of 2 D laser Doppler anemometry. Two weakly turbulent jets of Reynolds numbers, 1200 and 1800, are considered. In both test cases the secondary jet is fully absorbed by the primary one. The mean and turbulent flow structure of the stand-alone primary jet is compared to previous studies referring to the jet's development before and inside the self-similarity region. The flow field of interacting jets is then analyzed and discussed. Characteristic profiles are presented at locations within the merging and the mixing zones. In the early stages of development, the patterns of both jets can be identified. Within the merging region, besides the absorption of the secondary jet, the measurements indicate a spatial suppression of primary jet's characteristics. Further downstream, the profiles resemble to those of a standalone jet. Higher values of the mean and turbulent terms are observed while the profiles extend over a wider region, in accordance with the secondary jet's Reynolds number. Results of the present study demonstrate that skewness and flatness factors can be used as indicators of small scale mixing. (C) 2008 Elsevier Inc. All rights reserved.