Impingement cooling in a rotating curved square annular duct with crossflow effect from Rib-roughened surfaces

An experimental investigation was carried out to determine the effects of jets in crossflow on impingement heat transfer from rib-roughened curved duct with rotational speeds of 120 and 240 rpm. The jet impinged on curved surface in crossflow having repeated square ribs (3 2 3mm). The curvature of the duct was fixed and has a value of 300 mm. The rib height (e) was fixed at 1.5 mm and pitch-to-height ratio (p/e) kept at 2. The study covered jet Reynolds number in the range 6500 to 26000, and duct stream crossflow Reynolds number from 3250 to 13000 based on jet nozzle diameter, respectively, which gave M = 0.12 to 2. Results were presented for rotational, crossflow, roughened surfaces and curvature effects on local Nusselt numbers. Significant heat transfer enhancement was found for the present physical geometry and within the ranges of operating parameters considered in the study.