Evaluation of Flow Characteristics and Heat Transfer Efficiency in Tubes With Convex–Concave Corrugations

Abstract Given the complexity of corrugated tube forming processes, a method that enhances the hydrothermal performance (THCP) while reducing maximum corrugation depth holds significant practical value. In this work, a novel approach is proposed to improve THCP of corrugated tubes by employing convex–concave corrugations derived from simple corrugations, with the overall corrugation width and depth maintained constant. The feasibility of THCP enhancement via convex–concave corrugations is assessed qualitatively and quantitatively across a Reynolds number (Re) range of 5000–20,000, in comparison with simple corrugations. Furthermore, the effects of convex–concave corrugation structural parameters (depth, width, and curvature) on THCP are systematically investigated. Results demonstrate that compared to simple corrugations, convex–concave corrugations enhance THCP of heat transfer tubes by inducing stronger fluid disturbances and more intense fluid-wall impingement. Specifically, the optimal convex–concave corrugation configuration (W1 = 10 mm, W2 = 5 mm, H1 = 0.5 mm, H2 = 1 mm, R1 = 1 mm, and R3 = 25.25 mm) achieves a maximum THCP of 1.43, representing a 7.5% improvement over simple corrugations. This work confirms the feasibility of further enhancing THCP through convex–concave corrugations without altering the overall corrugation dimensions, and provides a valuable reference for the structural design of high-performance corrugated tubes.