Study On Sealing Characteristics Of Labyrinth Seals Of Aeroengines

Labyrinth seals are commonly used in aero-engine sealing system.They are mainly used to seal between rotor and rotor of aero-engine to prevent leakage of cooling air and lubricating oil.The geometric structure of labyrinth seals has a significant influence on the sealing performance.Improving the structure of labyrinth seals can ensure the safety and reliability of engine and improve the engine performance.In this paper,the influence of various parameters on the seal performance of labyrinth seals is systematically studied by means of numerical calculation.The sealing mechanism is analyzed through the internal flow field,and the improvement of the structure is of guiding significance to the practical project.According to the commonly used parameters range of labyrinth seals,the sensitivity analysis of the grid of labyrinth seals model was carried out,and an appropriate turbulence model and numerical calculation method were selected based on the experimental data of references.Commercial software FLUENT 18.2 was used to calculate and simulate the flow field distribution within the labyrinth seals of the straight type and the upper and lower step type,so as to intuitively understand the energy dissipation and flow mode of the internal labyrinth seals and the sealing principle.The influence of tooth number,throttling gap,tooth cavity shape,inclination Angle,inlet/outlet pressure ratio and rotation speed on the seal of the straight labyrinth seals and the relative axial position of steps and labyrinth seals on the seal of the stepped labyrinth seals are studied.The main research results of this paper are as follows:(1)Under the same pressure ratio,the straight labyrinth seal has the worst effect,while the lower step labyrinth seal has the best effect.(2)Influence of parameters:the leakage rate of labyrinth seals decreases with the increase of the number of teeth,increases with the increase of the width of labyrinth seals,and linearly increases with the increase of the throttling clearance.Among them,the number of teeth and the throttling clearance have a significant influence on the leakage rate.When the tooth cavity is close to square,the leakage amount is small,but the influence amplitude is small.Compared with the straight labyrinth seal,the right inclined labyrinth seal is not good for sealing,while the left inclined labyrinth seal is good for sealing.The optimal inclination Angle is about 45 degrees.Flow law is analyzed to improve and verify the model.The wall surface with a groove can effectively reduce the leakage and the effect of dense triangular groove is better.The leakage rate increases linearly with the increase of inlet/outlet pressure ratio,and the rotating speed has little effect on the sealing effect.Under the same pressure ratio,the parts with larger pressure distribution should adopt the sealing structure with better sealing performance.(3)The upper step labyrinth seal increases with the increase of the axial distance between the labyrinth seal and the step,while the lower step labyrinth seal increases first and then decreases with the increase of the axial distance between the labyrinth seal and the step.The tip seal structure of an engine is simulated and improved.(4)Pressure ratio,tooth cavity height and throttling clearance have the same influence rule on leakage of the two media.Right inclined labyrinth seal,labyrinth seal width and wall groove have opposite influence rule on leakage of the two media.The labyrinth seals in the cavity have almost no influence on the oil leakage.