Enhancement of the Thermohydraulic Performance in a Double Passage Square Duct with the Use of Inclined Ribs of 45°: A Comparative Computational Study

The modern gas turbines need to run at very high inlet temperature to promote their power output. Thus, improvements in cooling technologies play a significant role for enhancing the gas turbine blade life. In this paper, thermohydraulic performance (THP) of a two‐pass square channel with inclined ribs at 45° was scrutinized employing the k – ε realizable model with enhanced wall treatment in ANSYS Fluent. The calculations were performed for the rib pitch to height ratio ( p / e ) of 5‐10, rib height to hydraulic diameter ratio ( e / D h ) of 0.1‐0.2, and Reynolds number (Re) of 20,000‐40,000. Detailed analysis of the flow structure in a double passage square duct was carried out to understand the interaction of the rib and bend‐induced secondary flows and its contribution to heat transfer enhancement for the rib configurations with distinct p / e and e / D h , which was not available in any other existing numerical or experimental investigations. The results revealed that the ribs with higher e / D h generated the stronger stream‐wise secondary flows which led to the augmentation of the cooling performance with the disadvantage of pressure loss increment. The maximum THP of 26.55% was achieved with the ribbed configuration having p / e = 5 and e / D h = 0.1 at Re = 20,000. The new correlations were developed from the computational data to predict the normalized Nusselt number and friction factor (Nu/Nu 0 and f / f 0 , where 0 is the correlation), taking the e / D h and flow Re into consideration.