考虑动态摩阻的管道内水气耦合瞬变流的数值模拟

输水管道系统中经常会发生水气耦合瞬变流,可能会引起异常压力波动,甚至造成爆管事故。目前针对水气耦合瞬变流的研究很少考虑动态摩阻的影响,往往会低估瞬变过程能量衰减。对此,引入一种高效准确的简化加权类动态摩阻模型,建立考虑动态摩阻的水气耦合瞬变流模型。同时,采用虚拟塞法避免了特征线法在水气交界面的动态追踪时数值插值和求解的复杂。对比分析该模型计算结果与不考虑动态摩阻模型计算结果、试验数据,发现考虑动态摩阻的模型能更好地预测气团压力衰减和耗散,与试验压力峰值更为接近;入口压力越大,初始气团越小,动态摩阻对压力波动衰减的影响越大。

Simulation of Transient Flow in a Rapid Filling Pipe with Trapped Air Considering Unsteady Friction

Air pockets often entrapped in pressurized pipeline systems may cause abnormal pressure fluctuations,even pipe accidents.The research on transient flow in a rapid filling pipe with entrapped air pocket rarely considers the unsteady friction factors,which may underestimate energy attenuation.In this paper,an efficient and accurate simplified weighted unsteady friction model is introduced,and an air-water interaction transient flow model is established considering unsteady friction.At the same time,the virtual plug method is used to avoid the complexity of numerical interpolation and solution when the method of characteristics is used in the dynamic tracking of the water-air interface.The results of the proposed model are compared with those of the model without considering unsteady friction factors and the experimental data.It shows that the model considering unsteady friction factors can accurately predict attenuation and dissipation of the air pressure,and the results are close to the peak values of the experimental pressure.Besides,the effect of unsteady friction on pressure fluctuation is greater with larger inlet pressure and shorter length of initial air pocket.