长距离有压输水工程滞留气团迁移特性模拟研究

Simulation study on migration characteristics of trapped air mass in long-distance pressurized water conveyance systems

摘要

【目的】水气耦合作用及其模拟方法一直都是长距离有压输水管道水力学领域的科学难题，对比不同水气二相流模型对水气耦合作用的模拟效果，对长距离有压输水管道滞留气团演变与迁移过程研究具有重要意义。【方法】采取VOF、CLSVOF、CFD-PBM三种水气二相流模型对水流冲击管道盲端滞留气团的瞬变流案例进行模拟，从气团瞬变压力、气团形态变化等方面展开对比分析。【结果】结果显示：三种模型模拟第一波峰处最大压力的误差范围为0.78~1.45 m,第一波谷处最小压力误差范围为-0.55~-0.03 m,对于瞬变压力的模拟误差均在可接受范围内；CLSVOF模型模拟气团的破碎和聚并效果优于VOF和CFD-PBM模型，更适用于长输管道滞留气团的迁移问题分析。【结论】结果表明：采用CLSVOF模型，模拟了长输管道滞留气团在水流冲击下的迁移过程，发现滞留气团与水流之间存在明显的流速差，在水流拖曳作用下，气团以段塞流形式向下游输移，并通过流型图验证了模拟结果的正确性，证明了CLSVOF模型在长距离输水管道滞留气团迁移演变模拟方面的适用性。

Abstract

[Objective] The water-air coupling and its simulation method have long been recognized as a scientific challenge in the hydraulics of long-distance pressurized water conveyance pipelines. Comparing the performance of different water-air two-phase flow models in simulating the water-air coupling is essential for investigating the evolution and migration process of trapped air mass in long-distance pressurized water pipelines. [Methods] Three water-air two-phase flow models, VOF, CLSVOF, and CFD-PBM, were used to simulate transient flow scenarios of water flow impacting trapped air mass at pipeline dead end. A comparative analysis was conducted based on the transient pressure variations and morphological variations of the air mass. [Results] The result showed that the error range for the maximum pressure at the first peak simulated by the three models was 0.78 m to 1.45 m, and the error range for the minimum pressure at the first trough was-0.55 m to-0.03 m, both within acceptable error ranges in transient pressure simulation. The CLSVOF model outperformed both VOF and CFD-PBM models in simulating the fragmentation and coalescence of air mass, making it more suitable for analyzing the migration of trapped air mass in long-distance pipelines. [Conclusion] The result indicate that the CLSVOF model successfully simulates the migration process of trapped air mass under the impact of water flow in long-distance pipelines. A significant velocity difference between the trapped air mass and the water flow is observed. Under the drag force of the water flow, the air mass migrates downstream in the form of slug flow. The correctness of the simulation result is verified through flow pattern diagrams, demonstrating the applicability of the CLSVOF model in simulating the migration and evolution of trapped air mass in long-distance water conveyance pipelines.

关键词

瞬变流 / CFD / 数值模拟 / 有压输水管道 / 滞留气团 / 流型

Key words

transient flow / CFD / numerical simulation / pressurized water conveyance pipeline / trapped air mass / flow pattern

基金资助

国家重点研发计划“风险污染物全过程管控智慧决策支持平台集成与示范”(2021YFC3200905)

环北部湾广东水资源配置工程长距离大流量输水系统水流态势与“四预” 关键技术研究专题(XJLY-2022 HT-61)

新疆水利水电勘测设计研究院有限公司资助项目“复杂地质条件下超长深埋隧洞复杂断面水力学及安全输水”