朱錦洲Hsieh, C. S.C. S.HsiehShi, S. T.S. T.ShiWang, C. T.C. T.WangChu, Chin-ChouChin-ChouChu2009-02-092018-06-282009-02-092018-06-281991http://ntur.lib.ntu.edu.tw//handle/246246/123949https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006789739&doi=10.2514%2f6.1991-1816&partnerID=40&md5=af8c0ce353d81bf41677c2b432531f0fHawailAn experimental study has been conducted to investigate the flow of laminar vortex rings impacting on two different surfaces in an otherwise quiescent environment. The Reynolds number Rer (Γ/ν) is between 900 to 1800. The objective is to study the effect of the surface condition on the flow nearby as induced by vortex motions. The surfaces include a solid planar surface and a free surface. Vortex rings were generated by viscous effect as the flow leaves an orifice. The surfaces were located at four orifice diameters away. Detailed quantitative measurement was carried out by Laser Induced Photochemical Anemometry (LIPA), a nonintrusive visualization technique which enables simultaneous measurements of instantaneous velocity and vorticity at multiple locations on a planar area in unsteady flows. The measurements of unsteady vorticity distribution provide the insight into the intensification of vorticity, the decay of circulation associated with the primary vortex ring, the induced boundary layer near surfaces, and the formation of secondary vortex ring. Results show that a thicker boundary layer is formed as the vortex ring approaches the solid surface. In addition, the circulation of the primary vortex ring impacting on a solid surface decays faster than that on a free surface during stretching process. © 1991 by C. C. Chu et al.en-USAerodynamics; Boundary layers; Magnetohydrodynamics; Orifices; Plasma diagnostics; Reynolds number; Vorticity; Quantitative measurement; Quantitative study; Quiescent environments; Simultaneous measurement; Stretching process; Surface conditions; Visualization technique; Vorticity distribution; Vortex flowconference paper2-s2.0-85006789739