高真空多层绝热结构层间压力反演

Inverse Identification of the Residual Gas Pressure Distribution in High Vacuum Multi-layer Insulation

高真空是液氢温区多层绝热的基础,通过不同抽气工艺获得的多层绝热材料层间压力分布,使绝热结构性能有显著差异。为了预测多层绝热材料层间压力分布,并作为抽气工艺的评价依据,基于逐层传热学模型,首先通过理论计算建立由不同层间压力分布对应的温度分布组成样本集,应用截断奇异值分解获得其正交基。再根据某绝热结构样品实测的多层材料层间温度分布,采用吉洪诺夫正则化方法对正交基系数进行回归预测,重构层间压力分布,即反演获得了多层绝热材料的层间压力。通过与给定算例的对比验证,结果表明,采用本方法可以从易于精确测量的层间温度分布反演获得层间压力分布,更精确地预测多层绝热材料的性能。为评价、比较和优化液氢容器高真空多层绝热结构的抽气工艺提供参考。

High vacuum is a basic condition for the multilayer insulation at the liquid hydrogen temperature zone,and the residual gas pressure distribution in multilayer insulation materials(MLIs)obtained by different evacuation processes results in the obvious different performance of the insulation structure. In order to predict the residual gas pressure distribution of MLIs and use it as the basis for the evaluation of different evacuating processes,this study is based on the layer-bylayer heat transfer model. A sample set composed of temperature distributions corresponding to different residual gas pressure distributions of MLIs is established by theoretical calculation. The orthogonal basis was obtained by truncated singular value decomposition,and then the orthogonal basis coefficient was predicted by Tikhonov regularization method according to the measured temperature distribution of the MLIs,and the residual gas pressure distribution is reconstructed finally. It is validated by the given examples,and the residual gas pressure distribution can be obtained by the inverse identification method on the basis of the temperature distribution of the MLIs. Moreover,the performance of multilayer insulation materials can be predicted more accurately. This paper can provide a reference for the evaluation,comparison and optimization of the evacuation processes of high-vacuum multilayer insulation structures for liquid hydrogen containers.