Research On Deformation Coordination And Sealing Performance Of Shallow Groove Dynamic Pressure Seal Of Aero-Engine

With the continuous advancement of aviation industry technology,in order to achieve high propulsion efficiency in flight,the sealing performance requirements applied to key parts of the aircraft engine are more stringent.Limited by the traditional sealing structure,the existing seal is difficult to meet the sealing performance requirements of the aero-engine,and the developed shallow groove dynamic pressure seal(SG-DPS)is a new configuration seal with the advantages of long life,small leakage and adaptation,which can well adapt to the development of aero-engine performance and is the development direction of sealing technology in key parts of aero-engine.In view of the fact that the micro-motion compensation structure in high temperature environment is no longer suitable for O-ring as auxiliary seal,a micro-motion compensation structure based on metal C-ring is designed,and the structural parameters and compensation performance of metal C-ring are analyzed,and the preferred value of the compensation structure is obtained,which ensures the micro-motion compensation ability of the static ring component in high temperature environment.According to the designed sealing structure,the sealing performance analysis model is established based on the thermal-fluid-structure interaction analysis method.Considering the following changes of the physical parameters and temperature of the sealing medium,the deformation of the sealing end face is coupled to the boundary of the fluid wall,and the shear heat generated by the hot air of the end face is applied to the thermal field analysis boundary of the dynamic and static ring,so as to realize the calculation of heat-fluid-structure interaction.The calculation results are verified by literature comparison and experimental data,which provides a model basis for SG-DPS deformation and performance analysis.Through the analysis model,the influence law of working condition parameters on the deformation of the sealing end face is calculated and the strength analysis of each influencing factor is carried out,and the deformation coordination optimization scheme is proposed based on the strength analysis conclusion,which effectively reduces the deformation of the sealing end face and controls the sealing deformation gap type to convergent type,which reduces the influence of end face deformation on the sealing performance,so as to meet the high temperature adaptive needs of the sealing components when operating in high temperature and high-speed environments.The lubrication and sealing performance of air film at the end face of high-temperature and high-speed seals were studied,the mechanism of hydrodynamic pressure was revealed,and the effect of working conditions was analyzed.The essence of hydrodynamic pressure generation is the conversion of energy,the shallow groove of the end face introduces the high-pressure side medium into the sealing end face through the sudden change of groove shape and groove depth to produce a blocking effect,the fluid kinetic energy is converted into potential energy,and a "pressure wall" higher than the sealing medium is generated at the sealing end face to achieve the sealing of the medium,and the end face is lubricated by an air film with positive stiffness after opening.Based on the multi-parameter optimization conclusion of shallow groove of the end face,the preferred shallow groove structural parameters are obtained,and the eccentricity of component installation and shallow groove machining errors in practical applications are discussed,and the influence of uneven installation eccentricity and shallow groove processing on sealing performance is clarified.Aiming at the two low-speed and high-risk working conditions of start and stop,the end face contact friction analysis was carried out based on the dynamic contact analysis model.The end face friction and vibration characteristics were obtained,the noise reduction treatment of the vibration signal was carried out based on the singular value decomposition algorithm(SVD),the vibration frequency of the sealed component in the dry friction stage was obtained,and the frictional vibration intensity was characterized by power spectral density(PSD).The change law of the characterization parameters of three different start-stop conditions was analyzed,the strategy of reducing the risk of the start-stop stage was studied,and the effect of optimizing the start-stop operation on reducing frictional heat generation was quantitatively analyzed.Design and build a high-temperature and high-speed dynamic pressure sealing test bench to test the reliability of the developed sealing structure,in which the maximum deviation between the leakage test value and the calculated value of the model is less than 20%,indicating that the analysis model is accurate and reliable;Test the friction and vibration characteristics of dynamic pressure seals in the start-stop stage and the dynamic changes of the sealing gap during the running cycle.The results show that the developed SG-DPS has stable performance and good anti-interference performance,and the high-temperature micro-motion compensation structure is feasible.This paper provides a design basis and theoretical analysis basis for the structural design and sealing performance improvement of GS-DPS for aviation engines in high temperature and high speed environment through analysis and calculation and test methods.The analysis conclusion and test data provide a reference case for the application and promotion of dynamic pressure sealing technology in the aviation field.