| In view of the increasingly complex working conditions of the new generation of aeroengine,which leads to the continuous improvement of the sealing performance of the engine,the traditional grooveless air film floating ring seal has been unable to meet the requirements of the sealing stability of the high parameter engine,and often fails due to friction.A new type of spiral groove air film floating ring seal is urgently needed to replace it.The purpose is to improve the stability of the air film of floating ring seal under the synergistic effect of groove dynamic pressure effect and wedge effect,so as to achieve the performance requirements of floating up,improving stability and controlling leakage.Based on this,the flow field simulation method and test measurement analysis method are used to study the gas film sealing performance of the floating ring seal.The two methods confirm each other and verify that the new spiral groove gas film floating ring seal has the characteristics of excellent performance and high reliability.The performance of narrow ring micro clearance floating ring seal is studied by CFD software,and the internal flow field of grooveless air film floating ring seal and spiral groove air film floating ring seal are compared.The micro scale gas film model is established by SolidWorks software,and the three-dimensional geometry model is imported into ICEM software for structured grid generation.Then,the flow field is simulated by FLUENT software,and the pressure nephogram of the two models is obtained respectively,and the different leakage and buoyancy are calculated.The simulation results show that: with the increase of rotating speed,the leakage of the two sealing structures are basically unchanged,while the floating lift of the gas film increases linearly with the increase of rotating speed;and the leakage of the spiral groove gas film seal is always lower than that of the grooveless gas film seal,while the floating lift of the spiral groove gas film seal is higher than that of the grooveless gas film seal.This shows that,when the rotating speed increases,the sealing performance and stability of spiral groove gas film are better than that of grooveless gas film.With the increasing of the pressure difference,the leakage and buoyancy of the two types of sealing structures show a linear upward trend,and the buoyancy of the spiral groove gas film seal is significantly greater than that of the grooveless gas film seal,while the leakage of the spiral groove gas film seal is always less than that of the grooveless gas film seal.It shows that the spiral groove gas film floating ring seal has the advantages of less leakage and greater lifting force than the traditional non groove gas film floating ring seal under the same operating conditions.In this test,the leakage and eccentricity of floating ring seals with three different groove structures(no groove,spiral groove depth of 4 ?m,spiral groove depth of 8 ?m)are tested under different rotating speeds and medium pressures,and the change rules are analyzed to judge the sealing performance and stability of the sealing system,so as to verify the accuracy of simulation and obtain the optimal groove structure.The experimental results show that: with the increase of rotating speed,the leakage of the three types of groove structure slightly changes;with the increase of pressure difference,the leakage shows a linear upward trend,which is consistent with the simulation results;under the same rotating speed and pressure difference,the leakage of the spiral groove depth of 8 ?m is the smallest,followed by the spiral groove depth of 4 ?m,and the leakage of the floating ring seal without groove is the largest.The change amplitude of eccentricity reflects the change of gas film thickness and the stability of gas film.The smaller the amplitude of eccentricity is,the better the stability of gas film is.The eccentricity amplitude of three different groove structures decreases with the increase of rotating speed,and also decreases with the increase of seal pressure difference,which shows that the increase of rotating speed and pressure difference is conducive to the stability of floating ring gas film.Under the same rotating speed and pressure difference,the eccentricity amplitude of spiral groove gas film is far smaller than that of grooveless gas film seal,and the eccentricity amplitude of spiral groove gas film with the depth of 8 ?m is the minimum.To sum up,combined with the influence of rotating speed and pressure difference on the sealing and stability of three groove structures,the floating ring with the depth of 8 ?m of spiral groove has the best sealing effect.At present,the research on the floating ring seal structure of the new generation aeroengine is still in the research and development stage.This r esearch provides the theoretical basis and testing technology for further structural optimization research in the future.In the next step,we plan to use the method of combining numerical simulation and test to carry out multi-dimensional coordinated optimization of the parameters of the floating ring seal,such as groove type,groove depth and groove number,so as to make the new spiral groove air film floating ring seal early service laid a theoretical foundation. |
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