Experimental study on unsteady evacuation in multilayer insulation microcavities
To investigate the unsteady-state outgassing mechanism of residual gases within the Multi-Layer Insulation(MLI)of cryogenic,this study developed a simulated experimental plat-form that mimics the transient changes experienced during rocket launch and orbit.The platform was used to analyze the complex impacts of various parameters,such as pore group structure de-sign,aperture layout strategies,and spacer materials,on the transient release dynamics of rare-fied gases within the MLI.The results indicate that the relaxation time of MLI outgassing is ex-tremely slow,with outgassing persisting for over 270 hours and the maximum interlayer pressure remaining above approximately 2 Pa.This observation highlights a significant issue of parasitic heat leakages.As outgassing duration increases,the pressure differences within the MLI also in-crease depending on the configuration of the spacers.The MLI design with central circular aper-tures demonstrated a clear advantage in outgassing efficiency compared to designs with off-center or edge apertures.Additionally,the average pressure of circular and one-dimensional slit struc-tures was significantly lower than that of the serrated MLI under the same outgassing period.
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