A nonlinear dynamic model for non-contact mechanical seals with fluid-solid-thermal coupling effects

The dynamic characteristics of non-contact mechanical seals are affected by multi-physics and secondary seal non-linearities, which are ignored in traditional dynamic models. As a result, it struggles to accurately predict dynamic response of sealing systems under actual operating environments. To overcome these limitations, this work aims to propose an advanced dynamic model that integrates the fluid-thermal-solid coupling and nonlinearities of secondary seal. Based on the results of steady-state multi-physics coupling calculations, the transient data set of the primary seal is obtained using the perturbation method. A surrogate model between film thickness and dynamic parameters is established using machine learning method. The existing nonlinear model of the secondary seals is discretized and expressed numerically. A co-simulation solution method of the dynamic model is introduced to enable rapid calculation of dynamic responses. To verify the accuracy of the model, a novel method to measure performance parameters and dynamic responses of the mechanical seal is also proposed by applying force perturbation. The effectiveness of the proposed model is proven through comparisons with several experiments. The analysis reveals that the sealing system has good interference resistance and stability with design parameters. The hysteresis effect of the secondary seal is one of the key factors affecting tracking performance, which increases the risk of end-face wear and excessive leakage. This work provides theoretical guidance for multi-physics coupling and dynamic modelling of non-contact mechanical seals, laying the model and method foundation for failure analysis.