Research And Modeling Of Airtight Performance Of Three-dimensional Braided Seals

The air performance of three-dimensional braided seal is further discussed According to Darcy's Law,we present a computational model based on K-C equation and Kozeny theory for prediction.The model is combined with microstructure of the 3D braided seal,to predict the gas permeation as a function of fiber volume fraction,compression ratio and pressure drop across the seal.On the basis of numerical simulation,three-dimensional braided seals were designed and braided with different braided angles and single-wire diameters.Experiments were conducted to verify gas permeation in three-dimensional braided seal reliability of expression.The results are as follows:Based on the topological analysis and the volume element unit,the specific surface of three-dimensional four-direction and three-dimensional five-direction braided seals is respectively defined according to the formula of specific area.Then we present a computational model to predict the gas permeation of the strip seals and ring seals.The air performance of 3D braided sealing strips with different braiding angles shows that the braiding angle of 35° shows the best air performance,whose gas permeation decreased by 33.3%than the braiding angle of 20 °.Comparing the gas permeation of the three-dimensional braided seals with different monofilament diameters,it is found that the smaller the diameter of the monofilament yarn used,the better the air performance of the seals.The gas permeation of seal diameter of 7.5?m decreased by 40.9%than the diameter of 14?m seal.The influence of the diameter of the monofilament on the gas-tightness of the seal is more significant.It is indicated that fiber yarn with finer diameters can improve the air performance of the three-dimensional braided seals in the same fiber volume fraction,braiding angle and weaving structure.Comparing the measured and predicted gas permeation of the three-dimensional braided seals with different filament diameters and braid angles,they showed a relatively consistent curve trend at different compression rates.The accuracy of the model was further verified.