关键词: 埋地热油管道, 停输再启动, 数值模拟, 特征正交分解, 奇异值分解

Abstract:

The present paper proposed an efficient algorithm employing the proper orthogonal decomposition (POD) for the computation of the normal operation,shutdown and restart processes of buried heated pipelines.Firstly,the finite volume algorithm and finite difference algorithm were adopted to generate fundamental samples,and then eigenfunctions of the oil and soil temperature fields after pipeline shutdown and the restart flux were obtained by means of the singular value decomposition (SVD) algorithm.Further,spectral coefficients under the condition of arbitrary computation parameters were calculated by interpolation and finally the relevant physical quantities were rebuilt.By using this new algorithm,pipeline restart parameters under other conditions could be obtained very efficiently and accurately only by means of numerical computations with fewer input data.Case studies demonstrated that the deviations between the POD simulation and the direct numerical computation were less than 0.05℃ for temperature and 3% for the flow rate,respectively.Therefore,the computation efficiency was improved greatly by using the POD algorithm,and the average time consumption for the computation of one-group input data was about 20 min by using the numerical algorithm,while the POD algorithm averagely took only 0.1s or even less time.

Key words: buried heated pipeline, restart after shutdown, numerical simulation, proper orthogonal decomposition(POD), singular value decomposition (SVD)