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该文针对非驼峰式正虹吸管道进行了系列试验,量测了不同安装高度、不同水头差时管内呈现气团流流型时的过流能力和截面含气率。试验结果表明,气团流流型下虹吸管道过流能力随虹吸管安装高度的增大而减小,不能采用常规有压管流公式计算气团流流型时虹吸管过流能力。基于试验结果分析了影响气团流过流能力的因素,结果表明气体存在对流动沿程阻力系数影响不可忽略,过流能力计算时不能直接采用单一液相流动沿程阻力系数。不同安装高度时虹吸管内过流面积减小不是导致输水流量减小的唯一因素,除了考虑过流面积减小对过流量的影响外,还应考虑含气率大小引起的μ_0或λ变化对流量的影响。结合试验结果和数值分析,推导出适用于气团流流型下伪空化现象明显、安装高度不大于8 m的水平管段较长考虑含气率大小的虹吸管流量系数计算公式,修正和完善了有压管流过流能力计算公式,经检验公式计算误差小于±7%。
In this paper, a series of experiments on non-hump positive siphon pipes were carried out to measure the overcurrent capacity and cross-section gas-bearing capacity of gas-filled flow tubes with different installation heights and different head differences. The experimental results show that the flowability of the siphon pipe in the air mass flow regime decreases with the installation height of the siphon pipe, and the overcurrent capability of the siphon can not be calculated by the conventional pipe flow formula. Based on the experimental results, the factors influencing the air flow through the air mass are analyzed. The results show that the influence of gas on the drag coefficient is not negligible. The calculation of overcurrent capability can not directly adopt the drag coefficient of single liquid phase flow. The decrease of the flow area in the siphon at different installation heights is not the only factor that leads to the decrease of the flow rate of the water. In addition to the influence of the over-flow area reduction on the over-flow rate, the variation of μ_0 or λ caused by the gas-bearing rate The impact of traffic. Combining with the experimental results and numerical analysis, the formula for calculating the flow coefficient of siphon which is suitable for horizontal flow pipelines with obvious pseudo-cavitation under the air-mass flow pattern of not more than 8 m and the gas-bearing ratio is deduced, Pressure pipe flow through the formula, calculated by the test error less than ± 7%.