南水北调中线工程冬季输水冰情的数值模拟

Numerical simulation of ice regime in the water conveyance system during winter in Middle Route of South-to-North Water Transter Project

南水北调中线工程总干渠是由明渠和各种过水建筑物组成的树状系统,特点是线路长、过水建筑物类型多、冰水动力学响应过程复杂。本文将冰情发展模型与树状明渠系统复杂内边界条件下的渠道非恒定流模型进行集成耦合,开发了大型长距离调水工程冬季输水冰情数值模拟平台,提出了树状明渠系统复杂内边界条件的等效变换方法和计算冰盖前缘动态发展的虚拟流动法。根据实测的沿线气象资料和设计资料,利用该平台系统模拟了在寒冷气温条件下总干渠初冰、冰盖形成、发展和消融过程。分析了冬季输水的冰情特性及冰期输水能力,提出了冰期安全运行的水力控制条件,通过对典型年总干渠敞流期、冰盖形成期、稳封期、调度期以及开河全过程的模拟,给出了安全运行输水调度方案及建议。

The Middle Route of South-to-North Water Diversion Project is a tree-type water conveyance system consisted of long distance open channel and various hydraulic constructions. For simulate the complicated ice processes due to the ice-water dynamic response characteristics,a numerical modeling system was developed based on the integration of the river ice model and unsteady flow model with complicated inner boundaries. The equivalent transformation methods for inner boundaries and fictitious method to calculate the dynamic processes of ice cover are proposed. According to the meteorological observation data and design conditions in winter-spring period,the whole ice processes including ice cover forming,development,melting and break up as well as the ice-water dynamic response with the check gate operation involved for the Project were simulated. The ice characteristics and conveyance capacity of the project in winter were analyzed and the hydraulic control for safe regulation of the water conveyance system was suggested.