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An experimental investigation of impingement heat transfer in a rib-roughened trailing-edge channel with crossover holes

Posted on:2011-10-23Degree:M.SType:Thesis
University:Northeastern UniversityCandidate:Fong, Michael Ka HingFull Text:PDF
GTID:2442390002451113Subject:Engineering
Abstract/Summary:
A modern day turbine blade for a typical gas turbine usually contains rib roughened cavities which increases the cooling rate. There are several methods of cooling which include the impingement cooling method, the film cooling method, and the rib roughened cooling method. The trailing edge cooling cavity is focused in this study to provide a more efficient combination of the ribs to cool down the section.;The trailing edge cooling cavity of a typical gas turbine blade is modeled and put into a laboratory setting. There were eight different geometries tested, where the angle of the cross over holes, exit holes and the ribs were modified for each experiment. The angle of the cross over holes were varied between two selections, 0 degrees or 5 degrees, the alignment of the cross over holes and the exit holes were either inline or staggered, 2 or 4 exit holes were blocked, and the ribs were either present or not present. For each geometry setting, six Reynolds numbers were tested from 11,000 to 36,000. Liquid crystal thermography was used to measure the heat transfer coefficient on a target surface.;The variance of the Nusselt Number versus the Reynolds Number are compared for the different geometries and flow arrangements throughout the entire experimentation. The typical results show that the Nusselt Number increases as the Reynolds Number increases. For the experiment with the exit holes blocked, the heat transfer coefficients with the blocked holes were lower than the heat transfer coefficients with the open holes. It was also found that the case of the 5 degree tilt, inline flow arrangement with no bleed had the best heat transfer performance.
Keywords/Search Tags:Heat transfer, Holes, Cooling
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