Effects of Non-homogeneously Distributed Roughness on Turbulent Pipe Flow

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This proposal addresses a problem of critical importance to the hydroelectric power industry: to provide for the first time pressure drop data for non-homogeneously distributed roughness elements. These data are important as current data for roughness elements in pipes are restricted to uniform sand-grain type roughness or for roughness that is uniformly but sparsely distributed on a surface. Hydro Quebec have noted that in many of their hydro-electric penstock operations, that over a thirty year time frame, non-uniformly spaced and non-homogeneously distributed roughness elements are formed that gives rise to a drop in head (pressure) that translates into lowered electricity production with the concomitant loss of millions of dollars in revenue. This project will support the training of one M.A.Sc. student over two years and one Ph.D. student over four years, who will carry out a careful set of experiments to quantify these losses and to derive correlations that describe the effects of non-uniform roughness on skin friction (pressure loss) from which Hydro Quebec will then be in a better position to assess when to perform penstock cleaning. The data generated will fill a glaring gap in our knowledge on the effects of non-uniformly spaced and non-homogeneously distributed roughness elements. These data will be new to the scientific community and will generate numerous archival publications. These data, while of critical importance to Hydro Quebec will be communicated to other hydro-electricity generators in Canada through the scientific literature, and thereby will help improve Canada's overall hydro-electricity production efficiency as well as to provide critical information for scheduling penstock maintenance to achieve maximum benefit-to-cost.