基于动态摩阻的大落差输油管道 不稳定流动模拟

大落差输油管道高程起伏大，压力波动大，易由停泵、关阀等工况引发不稳定流动，导致管道局部压力降低和油品气化，引发弥合水击等现象。为准确预测大落差管道不稳定中流动压力、流量的变化，基于连续性方程、动量方程和能量方程，建立了大落差管道不稳定流动分析模型；结合Brunone-Vitkovsky动态摩阻模型，描述不稳定流动过程中的液体惯性加速带来的附加摩阻损失；采用特征线法和有限差分法求解模型。以某大落差管道中间泵站停泵工况为例，分析基于稳态摩阻与动态摩阻仿真的管道不稳定流动特征。结果表明：在稳定流动工况下，基于稳态摩阻和动态摩阻计算的管道压力、流量参数是一致的，但是在不稳定流动条件下基于动态摩阻计算的压力、流量比稳态摩阻模型值偏低。因此，基于动态模拟方法分析大落差输油管道的不稳定流动，对于提高管道压力、流量等工艺参数的预测精度，制定更加有效的不稳定流动安全防护措施具有重要意义。

Unsteady Flow Simulation of Hilly Oil Pipeline Based on Dynamic Friction Model

The hilly pipeline with the characteristics of great elevation fluctuation and pressure fluctuation is prone to unstable flow because of stopping the pump and closing the valve, resulting in local pressure reduction and oil gasification, and bridging water hammer. In order to accurately predict the changes of flow pressure and flow rate in the unstable pipeline with large drop, an analysis model of unstable flow in the pipeline with large drop was established based on continuity equation, momentum equation and energy equation; Combined with Brunone-Vitkovsky dynamic friction model, the additional friction loss caused by liquid inertial acceleration in the process of unsteady flow is described, and the characteristic line method and finite difference method are used to solve the model. Taking the pump stop condition of a large drop pipeline intermediate pumping station as an example, the unsteady flow characteristics of pipeline based on steady-state friction and dynamic friction simulation were analyzed. The results show that: under the steady flow condition, the pressure and flow parameters calculated based on steady-state friction and dynamic friction are consistent, but under the unstable flow condition, the pressure and flow calculated based on dynamic friction are lower than those calculated by steady-state friction model. Therefore, it is of great significance to analyze the unsteady flow of large drop oil pipeline based on dynamic simulation method to improve the prediction accuracy of process parameters such as pipeline pressure and flow, and to formulate more effective safety protection measures for unsteady flow.