Analysis Of Seal Rotordynamic Characteristics And Investigation On The Suppression Vibration Mechanism Of Novel Seal

Seal is the important component of turbomachinery,which can reduce the energy consumption of turbomachinery by reducing the leakage of working medium.However,with the development of turbomachinery to high parameters,the airflow induced force caused by seal becomes more and more larger,directly threatens the stability of rotor system.It is of great theoretical significance and engineering application value to carry out the study on seal rotordynamic characteristics and suppression vibration mechanism of novel seal.In this paper,theoretical,numerical and experimental studies were carried out.In the aspect of theoretical study,the mechanism of seal airflow excitatied vibration caused by hydrodynamic pressure effect was studied,novel negative dislocatied seal and floating convergent pocket seal were presented to reduce hydrodynamic pressure effect,and the suppression vibration mechanisms of the novel seals were analyzed.In the aspect of numerical study,the differences and applied ranges between the numerical methods of seal rotordynamic characteristics were analyzed,and the rotordynamic characteristics models of the novel seals were established.In the aspect of experimental study,the stability test rig of seal-rotor system and the test rig of floating seal self-concentric performance were designed and built.The study results show that,CFD transient single-frequency method and multi-frequency method can calculate and analyze seal rotordynamic characteristics at different rotor whirling frequency,which are more consistent with the actual working condition.Compared with the traditional cylindrical seal,the novel negative dislocatied seal has two divergent air wedges,can not form hydrodynamic pressure effect,thus it reduces the circumferential pressure difference and tangential airflow force,reduces the cross stiffness,improves the effective damping and logarithmic decrement rate,and effectively improves the rotor system stability.Compared with the traditional labyrinth seal,the novel convergent pocket seal improves the floating concentric force and effective stiffness,and improves the self-concentric performance of the seal.Under the same inlet pressure or initial eccentricity,the self-adapt concentric response of the novel convergent pocket seal experimental part is better than that of the traditional labyrinth seal experimental part.Using the novel convergent pocket seal instead of traditional labyrinth seal as the floating seal ring,can effectively improve the self-adapt concentric performance of floating self-concentric seal,and improve the rotor system stability.