Master of Science in Mechanical Engineering (MSME)
The potential of pulsed vertical jet in cross-flow for film cooling purposes was experimentally studied and is discussed in this Thesis. A single vertical jet placed in laminar cross-flow conditions was first characterized in steady state at relatively low blowing ratios ranging from 0.150 to 0.600, using Mie scattering visualization methods and hot-wire measurements. Wavelet spectral analysis and image quantification algorithms were applied to the velocity records and averaged visualizations to obtain quantitative data on the jet characteristic frequencies, penetration and coverage. Two different regimes characterized by different structures are identified and adapted scaling variables are provided. Trends in the jet penetration and jet coverage support the transition from one regime to another. The pulsed jet study is carried at duty cycles of 0.25, 0.50 and 0.70 and forcing frequencies of 0.5, 1.0, 5.0 and 10Hz for a total of 40 studied cases. Similar measurements and processing were applied to the forced experiments data. The presence of a starting vortex is observed in each case and an attempt to explain the dynamics of this structure is provided. The image quantification shows an overall decrease in the performance of the pulsed jet when compared to legitimate steady state cases, even though few cases exhibit a relative improvement.
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Bidan, Guillaume Francois, "Parametric study of a pulsed vertical jet in cross-flow" (2008). LSU Master's Theses. 622.
Dimitris E. Nikitopoulos