| In recent years, with the development of China’s urbanization and the improvement ofthe people’s living standards, there is growing public concern about the pollution and unequaldistribution of water sources. Accordingly, a large amount of long-distance water transmissionprojects are constructed. Water hammer protection is an important aspect of engineeringpractice and scientific research to guarantee the safe operation of long-distance watertransmission pipeline projects. Meanwhile, the friction is an important factor affectinghydraulic transient process.In this paper, the influence of different friction on hydraulic transients in long-distancewater transmission projects was studied on the basis of previous research results of frictionand pump-stopping water hammer.(1) The basic concept, generation mechanism, theoretical derivation and calculationmethod of pipeline friction were discussed; common used friction calculation methods in longdistance water transfer projects were analyzed and contrasted.(2) This paper made a systematic exposition on the principle of water hammercalculation, the differential equation of characteristic line and the basic procedure ofanalyzing pump-stopping water hammer by using computer program. The treatment offriction term was also studied.(3) Taking the water transmission projects in Xinjiang Fukang for example, the differentwater hammer calculation results by respectively using Ф.А.Шевелев formula andHazen-Williams formula were analyzed and contrasted. Meanwhile, on the situation that otherfactors (such as pipeline trend, velocity, pipe material) were approximately the same, theinfluence on hydraulic transients when pump-stopping water hammer happened by using thefriction value of different pipe diameter was studied.(4) Through analyzing, such the recommendations were putting forward for theprotection of pump-stopping water hammer in long-distance water transmission projects:adopting Hazen-Williams formula to calculate the friction was more accurate and safe thanФ.А.Шевелев formula; the pipeline of larger diameter with lower friction cause more harmthan smaller diameter with higher friction when pump-stopping water hammer happened, and more effective and proper measures should be taken to protect the safe operation oflong-distance water transmission projects. |
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