Research On Sealing Analyze Of The Space Vehicle And On-orbit Leakage Detection Technology

In order to guarantee the space mission succeed smoothly, the space vehicle musthas a high reliable sealing property. Therefore, we need to have an in-depth research ofspacecraft’s common structure of the sealing mechanism and the sealing performance.At the same time, we need to improve the ability of on-orbit leakage detection. Thisarticle has conducted these related research work, the main content includes thefollowing several aspects.Firstly, the formative factor of the leakage by metallic gasket sealing andpellet-cone sealing mechanism which are widely used at present is analyzed. Theresearch progress of these two sealing mechanism in the domestic and overseas aresummarized. At the same time, the existing methods of the spacecraft on-orbit leakagedetection are summarized,and the principle and applicability of these methods aresimple analyzed. The broad application prospect of the infrared imaging leakagedetection technology is pointed out.Secondly, the characterization parameters of the metal surface is introduced, andmodels of contact surface morphology description are summarized. The basic principleof the model is discussed, and the advantages and disadvantages of various models aresumed up. Besides, the general features of surface topography based on images of metalsurface outline from existing experimental measurement are mainly studied. Thus, themorphology of the sealing surface model and leakage path model are ascertained. Andfor the convenience of analysis leakage channels in molecular motion, the leakage pathmodel is reasonably simplified.Thirdly, the division of gas flow region and the characteristics of each region arebriefly analyzed, and the principles and basic ideas of direct simulation monte carlomethod are also introduced. Moreover, the flow properties of the gas molecules inleakage flow channel model under steady state condition are selective analyzed. Themodel of molecular leakage in contact surface seal channels is established, and theconcept of leakage annule is raised. The model is solved by matlab program using directmonte carlo method, and the molecules leakage probability of each leakage annule andthe total leakage probability of the whole sealing surface are calculated. Through theprogram. Besides, the influence from the amount of the annule layers and pressurebetween the sealing surfaces is considered. Finally, the leakage rate of the sealingsurface is calculated, and through the result, advice and guidance for sealing surfacedesign and installation are given.Then, the method of the infrared temperature leakage detection is studied. Thetemperature field distribution model of the pipeline under gas and liquid leakage isestablished, and the temperature field is simulated by Ansys. The simulation results show the model is correct.Finally, an experiment system of infrared temperature leak detection is introduced.And the liquid leakage experiment is carried out by the system. From the experiment,the infrared images of the pipeline by liquid leakage under vacuum conditions are taken.The feasibility of infrared temperature leakage detection method applied to the on-orbitleakage detection is validated.To sum up, the main work of this thesis is reflected in three aspects: the sealedsurface morphology model has been established in this paper theoretically; and theleakage model of gas molecule was set up by Monte Carlo method which is based onthe surface morphology model; besides, the reference to designing the sealingmechanism is provided by the results; the changes of tube’s temperature was conductedto the ground tests when the pipeline happened to leak, and the effectiveness of theleakage detection method of infrared temperature can be verified.