Experimental investigation of thermal performance in a rectangular channel using compound structure

Abstract

An experimental study was conducted to measure the heat transfer and pressure drop in a rectangular channel emphasizing a compound structure to improve the cooling performance of gas turbine blades. W shaped, semicircular, and multi semicircular shaped ribs with dimples are studied and applied to a lower surface of a channel. The experiment was carried out at a Reynolds number ranging from 10,000 to 32,000 and the ratio of pitch (P) to height (e) of the rib was 10. Also, the ratio of rib height (e) to channel hydraulic diameter (Dh) was 0.187  and the dimple depth (δ) to dimple diameter (D) ratio was 0.2. It was observed that the combination of ribs and dimple channel (compound channel) has an average of 23 %  more heat transfer than the ribbed channel. W rib compound channel shows the highest thermal performance and enhanced up to 30 % more heat transfer than semi and multi-semicircular compound channel. friction rise was observed in the compound channel compared to the ribbed channel.