3D simulation on water temperature change of diversion channel and optimal arrangement of multi-wells at high altitude and cold regions

Abstract: In the northwest high altitude and cold regions, it's easy to produce ice for the long distance of diversion channel of diversion power station. Pumping well water to melt ice is an effective method to solve the ice problem for diversion power station in winter. In order to investigate the effect of pumping well water to melt ice on the increase of channel water temperature, the second diversion channel of Hongshanzui Water Power Station in Manas River of Xinjiang was selected as the study area, and a three-dimensional turbulence numerical model was proposed to simulate the change process of water temperature of diversion channel under the condition of multi-well running at the same time. The change process of water temperature obtained from the simulation was compared with that from the prototype observation experiment, and the results indicated that the calculation results were in a good agreement with the prototype observation results. The average relative error between them was 4.61%, which verified the reliability of the numerical simulation. Thus, the water temperature change processes of diversion channel were simulated under the conditions of different discharge of well water, different discharge and temperature of channel water before wells, and different atmospheric temperature. Firstly, when the discharge and temperature of channel water were constant, and the discharge of well water was decreased by half or increased by half compared with the original value, the mixed water temperature was proportional to the discharge of well water and sensitive to it. At the same time, when the temperature of channel water was decreased and increased by 0.2 and 0.4 ℃, respectively, the mixed water temperature was proportional to the temperature of channel water and sensitive to it. It is concluded that it is the most effective way to pump well water to melt ice by increasing the discharge of well water and arranging the well group rationally. During the process of melting-ice wells running, each well not only affected the downstream water temperature, but also affected the upstream water temperature in some distance. According to the simulated results under the temperature of channel water of 0.1 ℃, the discharge of channel water of 10, 15, 20 and 25 m3/s, and the atmospheric temperature of -5, -10, -20 and -30 ℃, respectively, the different value of the ice-free water length of each well was calculated. The results showed that the length of the ice-free water for each well decreased with the increase of channel water discharge before wells and the decrease of atmospheric temperature. Based on the calculated length of the ice-free water for each well, the reasonably optimized results of the length of the ice-free water and the arrangement of the wells were proposed under different discharges of channel water before wells and different atmospheric temperatures. This study can provide valuable information for preventing ice hazards of diversion channel in the cold regions.