GUO Yong-xin, YANG Kai-lin, GUO Xin-lei, FU Hui (China Institute of Water Resources & Hydropower Research, State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Beijing 100038, China)

Abstract: In a long-distance large-scale pipeline system, the detained air pockets during filling are usually 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 prototype 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.

Key words: pipeline, detained air pockets, conveyance capacity, sensitivity analysis, similarity law

Published in: Journal of Hydraulic Engineering, Vol. 44, No. 3, 2013