干气密封环磨合过程摩擦振动信号混沌特性分析

磨合对防止干气密封环端面发生咬合、延长密封环使用寿命等具有一定影响,因而研究干气密封环在磨合过程中的变化特征,识别磨合状态有着重要意义。本文利用集合经验模态分解法（EEMD）提取端面间的摩擦振动信号。通过相空间重构,得到了摩擦振动信号的相轨迹和混沌参数。利用主分量分析法（PCA）和最大Lyapunov指数判别法,验证摩擦振动信号时间序列的混沌特性。并探究了吸引子结构演化轨迹以及其特征参数关联维数的变化规律。结果表明,当转速为500r/min、载荷为150N和450N时,磨合到稳定的过程中,各个摩擦振动信号时间序列的最大Lyapunov指数全部大于零、主成分分量谱图基本呈一条斜率为负的直线,摩擦振动信号具有混沌特征。而当密封环间的磨损状态由跑合阶段到稳定阶段变化时,其对应的摩擦振动吸引子变化趋势为更加“收敛-稳定”;混沌特征参数关联维数D的值皆随着磨合过程的进行由小变大,当摩擦进行到正常磨损阶段后D值都保持在较小范围浮动,达到平稳。因此,混沌吸引子以及关联维数D皆可反映密封环端面间的磨合过程,可用于干气密封环端面间磨合状态监测和识别。

Chaos Characteristics Analysis of Friction Vibration Signal in Running-in Process of Dry Gas Seal

Running-in can prevent the end face of dry gas seal ring from occluding and prolong the service life of seal ring. In this paper, 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 500r/min, the load was 150N and 450N, 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 can be concluded that the friction vibration signal has chaotic characteristics. When the wear state between the sealing rings changes 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 all 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.