Thermal–hydraulic optimization of a biomimetic leaf-vein cooling jacket for high-speed motorized spindles

High-speed motorized spindles operating under high power density are susceptible to excessive temperature rise and non-uniform thermal deformation, which deteriorate machining accuracy, thermal stability, and service life. Achieving uniform and efficient heat removal remains a critical challenge for spindle thermal management, particularly under compact structural constraints. To address this issue, a biomimetic leaf-vein cooling water jacket inspired by natural flow-distribution networks is proposed to enhance coolant uniformity along the stator surface. A sequentially coupled electromagnetics–fluid–structural modeling framework is established to accurately resolve electromagnetic heat generation, conjugate heat transfer, and thermo-structural deformation of the spindle system. Based on the coupled simulation results, a surrogate-assisted multi-objective optimization strategy combining response surface methodology and a genetic algorithm is employed to optimize key geometric and flow parameters of the cooling jacket, aiming to simultaneously reduce stator surface temperature and hydraulic pressure drop. Compared with the baseline configuration, the optimized design achieves a 2.46 % reduction in average stator surface temperature and a 3.21 % decrease in pressure drop without increasing pumping power, while also improving the uniformity of thermal deformation. Furthermore, comparative numerical analysis and indirect experimental validation using a conventional U-shaped cooling jacket confirm the predictive accuracy and engineering applicability of the proposed multiphysics framework. The present study provides a quantitative and reusable optimization route for thermal management design in high-performance motorized spindles.