Analysis Of Chaotic Characteristics Of Friction Vibration Signal Of Dry Gas Seal Ring And Its Tribological Properties

Dry gas seal is one of the most advanced seal forms at the present stage.Contact friction usually occurs in the start and stop stage and in the abnormal operation stage,which leads to a series of wear problems and affects the service life and utilization value of dry gas seal.Friction vibration is a common phen omenon of friction pair in the process of friction and wear,and the friction vibration signal contains a lot of information reflecting the running state of friction pair.In addition,chaos theory can well show the nonlinear characteristics of friction system and reflect the law of system change.Therefore,extracting the change characteristics of dry gas seal ring during friction and wear to master the state of friction and wear,and studying the change of tribological properties on the surface of seal ring according to chaotic parameters can provide theoretical basis for the study of friction of dry gas seal ring and the monitoring of wear state.This paper takes the start-stop stage of dry gas seal as the background,selects the appropriate working condition parameters to carry on the running-in wear test of dry gas seal ring.Then collectting the vibration signal during operation,and using the set empirical mode decomposition method(EEMD)for noise reduction to extract the appropriate friction vibration signal data.Finally,the friction vibration signal is analyzed by chaos theory.Using chaos theory to analyze the friction vibration signal between the dry gas seal rings,it is found that when the rotational speed is 500 r/min,the load is 150N,450N and 700N,the maximum Lyapunov of the friction vibration signal is all greater than zero in the process of running-in to stability,the principal component spectrum is basically a straight line with negative slope,and the morphology of the attractor has a certain distributed trajectory,so it is judged that the friction vibration sign al has chaotic characteristics.The change trend of friction vibration attractor from running and closing stage to stable stage is"convergence-stability".Correlation dimension D values of chaotic characteristic parameters change from small to large with the friction and wear proceeding.Hence,both chaotic attractors and associated dimension D can reflect the friction and wear process between the ends of the seal ring.Using the friction vibration signal attractor and its characteristic parameters to analyze the influence of different texture diameter and density(d=150μm,200μm,250μm and s_p=5%,10%,15%)on the tribological properties of the sealing ring,it is found that the friction vibration attractor of the 600 time surface seal ring is in a divergent state under the working condition of 300 r/min and load of 200 N.At this moment,the texture surface friction system is basically in a stable state,and the wear degree is small,while the surface vibration energy of the smooth surface ring is large,and the friction and wear are more intense,which indicates that the texture surface of the DLC film can effectively improve the tribological properties of the dry gas seal.The shrinkage degree of the friction vibration attractor increases with the increase of texture diameter and surface density,and the correlation dimension D increases gradually.This shows that when the texture diameter and surface density are large,the fine structure of the system is complex and the energy released by friction and vibration is weak.Thus,it can be obtained that the surface texture with diameter 250μm,area density 15%has the best tribological properties under the operating conditions of end load 200 N and rotational speed 300 r/min.