Test And Analysis Of Friction And Vibration Signal Of Dry Gas Seal

As a non-contact shaft seal,dry gas seal has the advantages of small leakage,low power consumption and long life.It is widely used in large rotating machinery equipment such as pumps and turbines.With the continuous improvement of aeroengines performance,the requirement for the leakage performance of dynamic seal is becoming stricter and stricter.In recent years,dry gas seals have gradually begun to be used in foreign high-performance aeroengines.However,the severe working conditions of aeroengine seals can easily cause severe friction between the interfaces of dry gas seal friction pair and lead to its failure.The friction performance of the dry gas seal end face is a key factor affecting its life and reliability.How to accurately obtain the wear state of the friction pair and optimize the friction performance of the dry gas seal friction pair under aeroengines working conditions is currently studied by scholars at home and abroad.The vibration signal acquisition system is composed of high-precision triaxial acceleration sensor,high-speed acquisition card and Lab VIEW signal system.It is used in this thesis to measure the friction vibration acceleration during the operation of dry gas seal.Based on the principle of harmonic wavelet packet transform in MATLAB,the vibration acceleration is peeled off,and the friction vibration signals of the dynamic and static rings are extracted,calculated,analyzed and verified.A method of extracting and analyzing the friction vibration signal of dynamic and static rings of dry gas seal is found out.Such a method could be used to extract the friction vibration signals of dry gas seal from many other disordered signals and monitor the detailed information of the sealing device in real time while its normal operation is not affected.It provides an innovative analysis way for the nondestructive monitoring and fault diagnosis of the dry gas seal devices used in aeroengine.Taking a specific aeroengine dry gas seal as the research object,a MMW-1vertical universal testing machine is used to set up a friction vibration test stand.Dry gas seal test pieces of different groove specifications and configurations are designed and manufactured.Research on the friction performance of these test pieces using MATLAB harmonic wavelet packet transform is carried out,and the following results and conclusions are got.(1)The friction and vibration signals between the dynamic and static rings extracted by the method described above are mainly located at the frequency band of(7000~8000)Hz.(2)The friction and vibration variation of two typical spiral grooves in this frequency band is then studied.The test results show that the vector and G of the X-axis and the Y-axis of the friction and vibration signals at the interface of the dynamic and static rings which have the spiral angle of 18 ° are both larger than those of the rings which have the angle of 16 °,while the direction of the vector and G is set to be consistent with the direction of the friction force.The friction wear scars on the3 D topography chart show that the 18 ° ring is more worn than the 16 ° ring.Such test results combined with the theoretical analysis of the friction mechanism give the main direction of friction and wear of the spiral groove ring during operation,and it is judged that the 16 ° ring has better service performance than the 18 ° ring,especially in the process of start-up and stop.(3)Finally,the comparison test on the friction performance between the micro-textured surface of the DLC film and the smooth surface of the seal ring is carried out.The vibration acceleration signals of different micro-textured surfaces are peeled off,extracted and compared in order to obtain the change rule of the friction vibration of different surface-textured seal rings.The test results show that the?200?m-5% textured surface has better anti-friction and anti-vibration properties.The abnormal friction and wear of the dynamic and static rings of dry gas seals is a “stopper” for the application of dry gas seals in aeroengines.In this thesis,a set of methods for extracting and identifying vibration signals of dry gas seals are researched,and the best match of the friction pair is got through experimental comparison.Those results provide a good technical basis and support for the application of dry gas seal in aeroengine.