UUnniivveerrssiittyy ooff KKeennttuucckkyy UUKKnnoowwlleeddggee University of Kentucky Master's Theses Graduate School 2001 PPIIVV MMeeaassuurreemmeennttss ooff CChhaannnneell FFllooww wwiitthh MMuullttiippllee RRiibb AArrrraannggeemmeennttss Harald Roclawski University of Kentucky, [email protected] RRiigghhtt cclliicckk ttoo ooppeenn aa ffeeeeddbbaacckk ffoorrmm iinn aa nneeww ttaabb ttoo lleett uuss kknnooww hhooww tthhiiss ddooccuummeenntt bbeenneefifittss yyoouu.. RReeccoommmmeennddeedd CCiittaattiioonn Roclawski, Harald, "PIV Measurements of Channel Flow with Multiple Rib Arrangements" (2001). University of Kentucky Master's Theses. 303. https://uknowledge.uky.edu/gradschool_theses/303 This Thesis is brought to you for free and open access by the Graduate School at UKnowledge. It has been accepted for inclusion in University of Kentucky Master's Theses by an authorized administrator of UKnowledge. For more information, please contact [email protected]. ABSTRACT OF THESIS Harald Roclawski The Graduate School University of Kentucky 2001 PIV Measurements of Channel Flow with Multiple Rib Arrangements ABSTRACT OF THESIS A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at the University of Kentucky By Harald Roclawski Lexington, Kentucky Director: Dr. Jamey Jacob, Assistant Professor of Mechanical Engineering Lexington, Kentucky 2001 Abstract of Thesis PIV Measurements of Channel Flow with Multiple Rib Arrangements A model of a gas turbine blade cooling channel equipped with turbulators and a backward facing step geometry was examined. Up to four turbulators oriented cross-stream and inclined 45◦ to the flow direction were mounted in the channel. The blockage ratio b/H of the turbulators and the height h/H of the backward facing step was 0.125 and 0.14 respectively. The number of turbulators as well as their size was varied. In a preliminary investigation, hot-wire and pressure measurementsweretakenforthreedifferentReynoldsnumbers(5,000,12,000,18,000)inthecenter plane of the test section. Subsequently, particle image velocimetry (PIV) measurements were made on the same geometries. Results of PIV measurements for a Reynolds number range of Re =600 b to 5,000 for the turbulators and Re =1,500 to 16,200 for the backward facing step are presented, h where Reynolds numbers are based on turbulator height b and step height h, respectively. Plots of the velocity field, vorticity, reverse flow probability and RMS velocity are shown. The focus is on the steady flow behavior but also the unsteadiness of the flow is discussed in one section. Also reattachment lengths were obtained and compared among the various turbulator arrangements and the backward facing step geometry. It was found that the flow becomes periodic after three or four ribs. For one turbulator, a very large separation region was observed. The magnitude of the skin friction factor was found to be the highest for two ribs. If the first rib is replaced by a smaller rib, theskinfrictionfactorbecomesthelowestforthiscase. Comparedtothebackwardfacingstep, the flow reattaches earlier for multiple turbulators. A dependency of reattachment length on Reynolds number was not observed. Keywords: PIV(ParticleImageVelocimetry),turbulator,channelflow,gasturbine,turbineblade cooling Harald Roclawski August 24, 2001 PIV Measurements of Channel Flow with Multiple Rib Arrangements By Harald Roclawski (Director of Thesis) (Director of Graduate Studies) (Date) RULES FOR THE USE OF THESIS Unpublished Thesis submitted for the Doctor’s degree and deposited in the University of Kentucky Library are as a rule open for inspection, but are to be used only with due regard to the rights of the authors. Bibliographical references may be noted, but quotations or summaries of parts may be published only with the permission of the author, and with the usual scholarly acknowledgments. Extensive copying or publication of the thesis in whole or in part requires also the consent of the Dean of The Graduate School of the University of Kentucky. THESIS Harald Roclawski The Graduate School University of Kentucky 2001 PIV Measurements of Channel Flow with Multiple Rib Arrangements THESIS A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at the University of Kentucky By Harald Roclawski Lexington, Kentucky Director: Dr. Jamey Jacob, Assistant Professor of Mechanical Engineering Lexington, Kentucky 2001 Copyright by Harald Roclawski 2001 Acknowledgments IwouldliketoacknowledgemyadviserDr. Jacobforhisguidanceandsupportformyresearch. I think I learned a lot from working with him during my research. I would also like to thank my committee members Dr. McDonough and Dr. Tagvai for their help. I would also like to acknowledge Dr. Beutner form the Air Force Office of Scientific Research (AFOSR) for sponsoring this project and the Fulbright Association for making it possible for me to study at the University of Kentucky. Furthermore, I would like to thank Prof. Dr.-Ing. Ch. Simon and Prof. Dr.-Ing. U. Zimmer- man from the University of Applied Sciences of Trier, Germany for supporting my application for the Fulbright scholarship. Last but not least, special thanks to my friends, my parents and especially Nicole, for their help and support. iii