寒区封闭引水渡槽中水温变化预测分析

甘肃引洮供水工程由于两条供水管线末端均不具备建设大型调蓄设施的工程条件,通过延长总干渠供水时间来解决调蓄不足的问题必须考虑冬季输水。针对这一实际问题,根据传热传质理论,建立了流固耦合对流换热三维数值模型,通过数值计算结果与室内模型试验结果进行对比研究,验证了数值模型的可靠性,表明其模型可用来对寒区封闭性渡槽内部水体在低温环境条件下的温度变化进行了预测分析。分析结果表明,虽然渡槽内水温与渡槽内的流量、入口水温、流速及环境温度等因素有关,但由于该渡槽结构及保温措施设计合理,并且有效控制水体在渡槽内的运行时间,水温降低幅度并不大,保证了在低温季节时水体在渡槽运行过程中水温不低于0℃,可有效防止渠体在寒区低温运行时结构冻害及冰灾现象的产生,进一步确保了封闭性渡槽的冬季输水安全。可为其它寒区引水工程的合理设计及安全运营提供科学参考。

Prediction analysis on water temperature in closed aqueduct in cold regions

Large water storages and diversion facilities can not be constructed at the ends of the two transportation lines of the Water Diversion Project from Tao River (WDP) in Gansu Province because of limit of engineering conditions. To solve this problem, water delivery time of the main channel has to be prolonged to winter. Based on the practical engineering condition and related heat and mass transfer theories, a three-dimensional numerical model for fluid-solid coupled convective heat transfer was established and validated by laboratory test result. The water temperature variation within the closed aqueduct under low-temperature condition in cold regions was predicted by solving the numerical model. The numerical results showed that the water temperature within the aqueduct was determined by the flow capacity, inlet water temperature, flow velocity, ambient temperature and et al. However, because of the effective design of the aqueduct, rational application of insulation and control of water flow time, the decrease of the water temperature was not obvious, and the water temperature in the aqueduct could be kept above 0℃, which ensured water supply in cold seasons. The study in this paper provides scientific reference for optimization design and safe operation of the other water diversion projects in cold regions.