Design And Performance Analysis Of Low Stiffness Sealing Structure

Static sealing technology is important to ensure the normal operation of the equipment,and is widely used in various fields,such as production and daily life.Under normal condition,the sealing medium is a kind of flammable,explosive,toxic or corrosive fluid.If the leakage accident happens,it will not only cause heavy economic losses,but also harm the personal safety.Therefore,the sealing performance and reliability of the sealing structure are particularly important.In order to ensure that the sealing performance of the static sealing structure can meet the usage requirements,researchers studied the performance of the sealing structure from both macroscopic and microscopic perspectives.From the view of macro-perspective,the sealing performance of the research mainly through the experiment to measure the leakage rate of different sealing structures to ensure the reliability of the sealing performance,or using the finite element method simulating the sealing structures to ensure that the force of the gasket can meet the usage requirements.The sealing performance test of different structures by experiments not only has a high manufacturing cost,but also has a long test period.Although the method of simulation can analyze the stress state of the sealing structure under different working conditions,the leakage rate cannot be accurately predicted.From the view of microperspective,the sealing performance is studied by statistically analyzing the surface topography of the sealing surface.The leakage rate on the sealing surface is calculated based on an assuming a reasonable form of leakage channel.However,due to the variety of processing of the sealing surface,the difference in the contour characteristics of the surface causes the leakage channels of various forms existing certain limitations,so the prediction of the sealing performance also has a big error.At the same time,due to the large difference in size between microscopic research and macroscopic structure,it is difficult to predict the leakage rate of macroscopic sealing structures.This paper proposes a method for calculating the leakage rate on the sealing surface by using the equivalent leakage gap,so that the leakage rate on different sealing structures can be quickly predicted to ensure the reliability of the sealing performance.The research content of this paper is as follows:(1)The relationship between the equivalent leakage gap and the contact pressure is calibrated by the leak rate calibration experiment.The finite element model of different sealing structures is established,and the contact pressure on the sealing surface is obtained and converted into the equivalent leakage gap.Using the Reynolds equation to calculate the flow through the sealing gap,which is the leakage rate on the sealing surface,the prediction method is verified by experiments.(2)The influence degree of the manufacturing error and assembly error of the sealing structure on the sealing performance is calculated by the static sealing structure leakage rate prediction method.Through the model analysis,it is found that the assembly offset of the sealing structure has the greatest influence on the sealing performance.Although the manufacturing error of the gasket and the assembly deflection have little effect on the sealing performance,when these errors are simultaneously present in the sealing structure,the impact will accumulate.(3)The analysis of the two-dimensional sealing structure model of fuel cell stack founds that if the peaks of the gaskets are not able to be opposite when the multi-peak gaskets are assembled,the sealing structure will produce a certain amount of offset during assembly,which reduces the reliability of fuel cells assembly.The assembly error of the stack has great influence on the sealing performance of the fuel cells,and needs to be strictly controlled during assembly.