| Rotating machinery will face complicated working conditions and alternating load when it is in service,resulting in the traditional seals used at its shaft ends failing to meet the working conditions.Therefore,it is especially important to develop a seal with low leakage,high stability and long life.Based on the floating characteristics of the floating ring and the micro-gap dynamic pressure performance,a cylindrical gasmembrane dynamic pressure sealing device with floating and micro-gap characteristics was proposed,and a rectangular groove,a streamlined groove,an optimized rectangular groove,and an optimized streamline groove were designed.Taking fluid simulation and prototyping test as the starting point,From the theoretical simulation and experimental research,the micro-gap dynamic pressure seal was deeply studied,which solved the problems of large leakage of traditional seal,poor stability and short service time.In this paper,the spatial structure characteristics of the micro-gap wedge distribution of cylindrical gas film dynamic pressure sealing were considered,and the influence of micro-groove,micro-gap structure and eccentric structure on mesh division was considered.Structured meshing of four slotted fluid domains was performed using a unique block mapping technique.Then use Fluent software to simulate and analyze the micro-gap fluid domain.The pressure distribution and velocity distribution of four kinds of groove fluid domains were obtained respectively.The influence of working condition parameters and groove parameters on the performance parameters of cylindrical gas film dynamic pressure sealing was analyzed.The results show: The cylindrical gas film dynamic pressure seal is more stable in service under low pressure and high speed working conditions;As the rotation speed increases,the leakage amount gradually decreases and eventually approaches equilibrium,and the leakage amount increases rapidly with the pressure gradually increases;As the speed and pressure increase gradually,the buoyancy force will gradually increases;The buoyancy force of streamlined groove and the optimized streamline groove is larger than the rectangular groove and optimized the rectangular;Optimized streamlined groove have a small amount of leakage,while rectangular groove have a large amount of leakage.This paper builds a test platform of cylindrical gas film dynamic pressure sealing test parameters.The transmission system uses a high-speed electric spindle to drive the sealing system,which can be freely adjusted from 0 to 37000r/min,thus reducing intermediate transmission,improving stability and ensuring accuracy of test data.The main purpose of the pneumatic system is to provide a stable,clean,impurity-free and inert gas with a certain pressure to the cylindrical gas film dynamic pressure sealing device;the test system mainly tests the rotational speed of the cylindrical gas film dynamic pressure sealing device and the pressure of the sealing medium and the amount of leakage;The sealing system adopts a double-end “back-to-back” mounting arrangement,including designing and machining of prototype,laser grooving,and 3D phenetic analysis of grooved and non-grooved areas,through a 3D surface profile topography instrument.3D white light interference observation and analysis of cylindrical grooved and non-grooved areas.The results show: the surface roughness of the groove bottom basically meets the test requirement.Two kinds of cylindrical gas film dynamic pressure sealing device structures(namely rigid support structure,flexible support structure),and the effect of different groove type and floating ring material on sealing performance.After a test and comparative study on different support structures,groove types and floating ring materials.The results show: the sealing performance of the optimized groove type is better than that of the initial groove type,and the flexible support structure has better service effect;Compared with high-strength aluminum alloy(7075)materials,graphite materials have better sealing service performance.And it has better self-lubricating property,thereby improving the friction performance of the cylindrical friction pair,reducing the friction coefficient and reducing the wear and temperature rise;Then use the white light interference 3D surface profile topography instrument to observe and analyze the four grooved areas after service.The results show: The non-groove areas of the four grooves s are more severely worn,and the outer surface of the streamlined groove is minimized,and the outer surface of the two initial groove is more scratched,so that the optimized streamline groove has better sealing service performance. |
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