| Summary: | This thesis examines the advantages of implementing ribs on the mid-chord cooling channels of turbine airfoils. The scaled model of rectangular cross-section channels with aspect ratio of 3 are tested with 5 different configurations. The heat dissipation inside the channel is modelled as a heated wall boundary condition, and to simulate such condition, 3 patches of heaters were placed on a polyurethane block along the test section. Liquid crystal sheets were then adhered to
the block on top of the heaters. The 2 general geometries tested are Baseline Coriolis (Configurations 1-4) and 45Deg Ribs (Configuration 5). The first and second configurations consist of 14 ribs implemented on the liquid crystals at an angel of 45deg opposite to each other, and 7 ribs at 90deg on the plexiglass. The third and fourth configurations have the same placement of ribs, except the 14 on the liquid crystal side are at a reversed 45deg angle. The four configurations have a
height-to-hydraulic-diameter ratio (e/D<sub>h</sub>) of 0.14 and height-to-width ratio (e/w) of 0.899, and pitch-to-height ratio (P/e) of 10. The difference between the 2 pairs of configurations are that one of each pair has 9 bleeding holes of 9/16 in diameter along the test section. The fifth configuration consists of 9 of the same bleeding holes and 6 ribs on each side at an angle of 45deg. The height-to-hydraulic-diameter ratio (e/D<sub>h</sub>) is 0.12 and
height-to-width ratio (e/w) of 0.818, and pitch-to-height ratio (P/e) of 11.78. The local and average heat transfer coefficients were calculated with data measured consolidated into enhancement factors for comparison. From this study, it can be concluded that: 1. configurations with bleeding holes tend to have larger Nusselt numbers and enhancement factors for similar local Reynolds numbers. 2. Configurations with reversed 45deg ribs on the liquid crystal side tend to have a tend to
have larger Nusselt numbers and enhancement factors for similar local Reynolds numbers. 3. The fifth configuration tends to have a steadier decrease in enhancement factor as the local Reynolds number increases. This is likely due to the more uniform placement of ribs. A CFD modelling of the experiments can be performed to support the results and correlations.
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