Thermal and Flow Characteristics of Perforated Blockages in Confined Channels

Heat transfer, friction, and thermal performance of perforated flow blockages are measured in a confined rectangular channel (W/H = 9.375, Re = 7700–12,200). Wall temperature fields are measured by thermochromic liquid crystal thermography. Flow structures are computed with SST k–ω RANS simulations (grid convergence index 7.1%). Twelve configurations at an equal open-area ratio of 27.6%—compared at matched open-area for the first time—cover single-row and double-row perforations, inline and staggered alignments at P = 1H–3H. Four flow regimes are identified: direct jet penetration, recirculating wake, merging-zone interaction, and extended reattachment. Single-row staggered blockages at P = 1H give the highest enhancement, Nu¯/Nu¯0 ≈ 5–6. The double-row geometry (smaller holes in two rows at constant open-area) reduces the friction factor by more than 50% and reaches the maximum thermal performance factor, η ≈ 1.3–1.4, for the inline arrangement at P = 1H. Configurations that maximize Nu¯/Nu¯0 also maximize the Nusselt number uniformity index, applied here to perforated blockages for the first time, σNu. σNu remains below 40% for all configurations. Double-row arrangements at P = 2H give the best balance of η and σNu. A regime map summarizes these results for configuration selection in aero-engine internal cooling and related confined-channel systems.