Abstract:Running-in can prevent the end face of dry gas seal ring from occluding and prolong the service life of seal ring. The ensemble empirical mode decomposition method (EEMD) was used to extract the friction vibration signal between the end faces. The phase trajectories and chaotic parameters of friction vibration signals were obtained by phase space reconstruction. Principal component analysis (PCA) and maximum Lyapunov exponent discrimination method were used to verify the chaotic characteristics of friction vibration signal time series. The evolution trajectory of attractor structure and the change rule of correlation dimension of its characteristic parameters were explored. The results showed that when the rotational speed was 500 r/min, the load was 150 N and 450 N, the maximum Lyapunov indexes of each friction vibration signal time series were all greater than zero, and the principal component spectrum was basically a straight line with negative slope. So, it could be concluded that the friction vibration signal had chaotic characteristics. When the wear state between the sealing rings changed from run-off stage to stable stage, the corresponding change trend of friction vibration attractor was “convergence-stability”. The value of correlation dimension D of chaotic characteristic parameters changed from small to large with the running-in process. And when the friction was carried out to the normal wear stage, the value of D was kept floating in a small range to achieve stability. As a result, both chaotic attractor and correlation dimension D can reflect the running-in process between the ends of the seal ring, and can be used to monitor and identify the running-in state between the ends of the dry gas seal ring.