Type of Document	Thesis
Author	Davy, Charney Anchilyn
URN	etd-08182004-093757
Title	Surface Flow Measurement of Supersonic Impinging Jets
Degree	Master of Science
Department	Mechanical Engineering, Department of
Advisory Committee	Advisor Name Title Farrukh S. Alvi Committee Chair Chiang Shih Committee Member George Buznya Committee Member Jonathan Naughton Committee Member
Keywords	Jets Surface Flow Supersonic
Date of Defense	2003-12-01
Availability	unrestricted
Abstract Impinging supersonic microjets have been studied experimentally where both surface pressure and shear stress measurements and flow-field visualizations have been obtained. Microjets with diameters of 400 and 1000 microns have been investigated, operating at pressure ratios of 3, 5, and 8 and impinging plate distances of 2 to 8 diameters. The primary work concentrates on the application of oil-film interferometry to the flowfield in order to determine the surface shear stress. The results of this study indicate that high shear stress levels exist over a significant region around the impingement point and that the shear stress gradients are very high. For example, at a pressure ratio of 8, shear stress value at 2 and 11 nozzle diameters from the impingement point was found to be 300 Pa and 50 Pa, respectively. The shear stress distributions were compared with surface pressure distributions and to the limited computational results available for impinging jets. Although, a direct comparison is impossible due to lack of such data in literature, the trends observed in the present study appear to agree with those of larger supersonic impinging jets. The measurements indicate that oil-film interferometry provides repeatable, and reliable shear stress data in this complex flowfield - dominated by regions of high shear and large pressure gradients – which may not be amenable to other methods. The study also suggests some improvements, which can be implemented to further improve its reliability.
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