大型管道输水系统充水过程滞留气泡对输水能力的影响

Effect analysis of the detained air pockets to the conveyance capacity in large-scale pipelines

通常认为长距离大型管道输水系统充水过程中,滞留气泡对系统的高效输水和安全运行有重要影响。为了评估滞留气泡对输水能力的影响,首先对影响管道输水能力的因素进行敏感性分析,并基于气体热力学原理,建立原型、模型之间气泡的几何比尺关系,为评估滞留气泡对输水能力的影响提供理论依据。针对南水北调中线北京段西四环暗涵的现有通气孔设计,结合模型试验结果,分析了原型中滞留气泡对输水能力的影响,认为在现有通气孔布置的情况下,原型中滞留气泡对管道流量或输水能力的影响小于模型中测量所得的1.07%,在实际工程运行中可忽略。

In a long-distance large-scale pipeline system , the detained air pockets during filling are usual ly considered that they have a significant impact on the conveyance efficient and safe operation. To assess the effect of detained air pockets , the sensitivity analysis of conveyance efficient is performed firstly. Based on the thermodynamic principles , the geometry relationships of air pockets between prototype and model are derived , which provide a theoretical basis to assess the effect of detained air pockets. Under the condition of the existing air vents layout of Beijing West 4th Ring Road culvert in South-to-North Water Diversion , based on the physical model test , the effect of detained air pockets upon the conveyance capacity in proto type are qualitatively analyzed , and we derived that the existing layout of air vents is reasonable , and the decreased conveyance capacity due to air pockets in prototype is less than 1.07% in the model. The effect is so little that it can be ignored in the project operation.