DOUBLE WALL COOLING OF A FULL COVERAGE EFFUSION PLATE WITH CROSS FLOW SUPPLY COOLING AND MAIN FLOW PRESSURE GRADIENT

摘要

Experimentally measured results are presented for different experimental conditions for a test plate with double wall cooling, comprised of full-coverage effusion-cooling on the hot-side of the plate, and cross-flow cooling on the cold-side of the plate. The results presented are different from those from past investigations, because of the addition of a significant mainstream pressure gradient. Main stream flow is provided along a passage with a contraction ratio of 4, given by the ratio upstream flow area, to downstream flow area. With this arrangement, local blowing ratio decreases significantly with streamwise development along the test section, for every value of initial blowing ratio considered, where this initial value is determined at the most upstream row of effusion holes. Experimental data are given for a sparse effusion hole array. The experimental results are provided for mainstream Reynolds numbers of 128400 to 135300, and initial blowing ratios of 3.6, 4.4, 5.2, 6.1-6.3, and 7.3-7.4. Results illustrate the effects of blowing ratio for the hot-side and the cold-side of the effusion plate. Of particular interest are values of line-averaged film cooling effectiveness and line-averaged heat transfer coefficient, which are generally different for contraction ratio of 4, compared to a contraction ratio of 1, because of different amounts and concentrations of effusion coolant near the test surface. In regard to cold-side measurements on the crossflow side of the effusion plate, line-averaged Nusselt numbers for contraction ratio 4 are often less than values for contraction ratio 1, when compared at the same main flow Reynolds number, initial blowing ratio, and streamwise location.