Influence of inlet pressure disturbance on transient performance of liquid oxygen lubricated mechanical seal and rub-impact phenomenon caused by excitation overload

The dynamic stability of the non-contacting mechanical seal (NMS) under variable working conditions is a vital factor for the reliable operation of rotating equipment. This paper presents a transient dynamic model to investigate the parametric response of liquid oxygen lubricated NMS under inlet pressure disturbance, which comprehensively considers asperity contact, micro-clearance lubrication and dynamic motion of a flexible mounted ring. Meanwhile, various forms of rub-impact phenomenon and dynamic instability caused by excitation overload are also analyzed. Lastly, an experimental research is proposed with diverse sensors to monitor the parameter data under pressure disturbance. In addition, the characteristics of acoustic emission signals when rub-impact of friction pair occurs are further investigated and processed, including various impact forms and location method. •A transient dynamic model considering rub-impact of liquid film seal is proposed.•Three types of rub-impact and instability caused by excitation overload are analyzed.•Overall response consists of mutation, transition and periodic fluctuation stage.•Different acoustic emission (AE) signals correspond to various rub-impact forms.•The rub-impact frequency obtained by AE sensor is equal to the rotating frequency.