Aerothermal performance of a rotating two-pass furrowed channel roughened by angled ribs

Abstract

• A compound-HTE method with angled ribs and furrowed passages was devised for cooling of gas turbine blades. • Without rotation, Nu 0 were raised to 4.9–4.77 times D-B levels with f 0 between 33.15 and 35.92 times Blasius equation values. • With rotation, overall Nu ( f ) on leading and trailing walls were 1.03–2.0 (1.10–1.66) and 1.02–1.91 (1.12–1.74) times Nu 0 ( f 0 ). • Thermal-performance indexes of static (rotating) channels were 1.53–1.45 (2.39–1.48). The aerothermal performance of a novel compound heat transfer enhancement method is assessed by measuring the full-field endwall Nusselt number map and Fanning friction factors of a rotating two-pass furrowed channel roughened by angled ribs. The tested Reynolds numbers, rotation numbers, and buoyancy numbers lie in the respective ranges of 5000–15,000, 0–0.4, and 0–0.183. Under the combined effects of the ribs and furrowed passages, the endwall-average Nusselt numbers of the static channel are upraised to 4.9–4.77 times the Dittus–Boelter levels. With rotation, the worst cooling condition develops at a rotation number of 0.05 with the spotted heat-transfer impediments to 0.77 and 0.82 times the static channel references on the leading and trailing endwalls, respectively. By raising the rotation number from 0 to 0.4, the Nusselt numbers on the stable endwalls are initially reduced from the static-channel levels and then converted to increase with the rotation number; however, the friction factors increase continuously. Over the rotating unstable endwalls, both the Nusselt numbers and the friction factors increase along with rotation number. When the buoyancy number is increased, the local Nusselt numbers on the leading and trailing endwalls increase with a negligible impact on their distribution patterns. The thermal-performance indexes of the rotating channel are reduced by increasing Reynolds number. To aid the relevant applications, two sets of experimental correlations are devised to determine the regional average Nusselt number and Fanning friction factor of the rotating two-pass furrowed channel fitted with angled ribs.