The main performance of bellows mechanical seal failure

Bellows mechanical seal has the advantages of good sealing performance, high reliability, long life, good stability and good vibration resistance than other sealing devices, but as the working environment of bellows gradually begins to develop into complex, bellows mechanical seal device due to multi-body multi-field coupling excitation prompted mechanical seal rotor system coupling vibration, resulting in seal ring deformation and thermal cracking, excessive wear of sealing surface, polymerization and coking, bellows Loss of elasticity or fracture, etc., mainly manifested as follows.
First, the bellows mechanical seal device is a multi-body system with rigid-flexible-liquid coupling composed of bellows (flexible body) - seal ring (rigid body) - friction sub-film (liquid) - rotor (rigid body) and thermal-fluid-solid multi-field composition of multi-field coupling system, so the interaction and excitation between rigid-flexible-liquid multi-body and thermal-fluid-solid multi-field composition of a complex non-linear rotor system with multi-body multi-field coupling.
The deformation and temperature of the seal ring friction sub-interface are mutually coupled to influence and promote the formation of a local high load area at the seal ring friction sub-interface, causing the liquid film at the seal ring friction sub-interface to vaporize and form an unstable state of liquid-gas mixed phase, while the mutual coupling of the bellows and the friction sub-film nonlinear damping causes dynamic vortex motion and self-excited oscillation of the liquid film, accelerating the non-linear rotor system composed of bellows-seal ring-friction sub-film-rotor. The non-linear process of multi-body multi-field coupling system causes thermal deformation, excessive wear and thermal cracking of the friction sub-seal ring, resulting in mechanical seal failure.
Under the complex working conditions with high parameters, the thermal deformation and various coupling vibrations occur in the bellows, seal ring, liquid membrane and other rigid-flexible multi-body structures due to the coupling excitation of rigid-flexible-liquid multi-body and thermal-fluid-solid multi-fluid coupling, which will also affect the stability of the fixed end face and the abnormal fatigue tear and resonance caused by the intense vibration.