Thermal–Fluid–Solid Coupling Analysis of Enhanced Heat Transfer and Thermal Stress in Shark Skin Micro-Rib Tubes

A multi-field coupled numerical model integrating fluid flow, convective heat transfer, and thermal stress is established for a shark-skin-inspired V-shaped micro-rib heat exchange tube. Using the shear stress transport (SST) k-ω model, its thermal–hydraulic performance is compared with a smooth tube, revealing the mechanism of vortex-induced thermal boundary layer disturbance. Based on an L32 orthogonal array and range analysis, the sensitivity of seven geometric parameters to pressure drop and heat transfer power is quantified. A one-way thermal–fluid–solid coupling technique maps the non-uniform temperature field onto the solid domain and solves thermal strain and stress via thermoelastic constitutive equations. Results indicate that the shark skin structure induces dense prismatic vortices, improving the heat transfer coefficient by 21.7% while incurring a 245.4% increase in pressure drop. Among the parameters, hrib/P exerts the most significant influence. Thermal stress concentration occurs at the rib–root junctions. Under specific nuclear power plant seawater heat exchanger conditions, the maximum thermal stress is about 42 MPa, far below the TA2 (Grade 2 titanium alloy) yield strength, ensuring the design remains within the linear elastic safety range without plastic yielding.