Analysis of Mechanical‐Electrical‐Hydraulic Coupled Vibration Response Characteristics of Thermal Control Circulating Pumps Supported by Water‐Lubricated Bearings

The operational reliability of thermal control circulation pumps is significantly restricted by the multi‐physics coupled environment. To reveal the vibration transmission mechanisms and dynamic response characteristics under multi‐field coupled excitations, a multi‐DOF coupled dynamic representation of the overall system, incorporating the rotor, volute, and pump casing, is established. The proposed model comprehensively accounts for the unbalanced magnetic pull, dynamic hydraulic excitations, and nonlinear water film forces of the bearings. Numerical solutions of the coupled nonlinear dynamic equations are obtained using the Newmark‐β method with Newton–Raphson iteration, thereby examining the influence of key parameters on the system's nonlinear responses in the time and frequency domains. The results indicate that the degradation of the x ‐direction support stiffness of the screw‐supported interface reduces the local foundation stiffness of the pump casing and triggers severe nonlinear responses and abrupt amplitude jumps. A moderate increase in the bearing clearance weakens the water film constraints, which not only exacerbates the nonlinear vibration of the rotor but also amplifies the transmission of dynamic loads to the pump casing. In addition, the reduction of the stator‐rotor air gap intensifies the electromagnetic negative stiffness. The competition between this negative stiffness and the positive stiffness of the water film not only induces a shift in the static equilibrium position of the rotor but also causes a sharp decline in the mechanical transmission capacity at the bearing support interface, effectively impeding the transmission of dynamic excitation loads to the external casing. The multi‐body dynamic model formulated in this study provides a solid theoretical foundation for the anti‐vibration optimization design of thermal control circulation pumps.