| The technology of pumping well water to melt ice is an economic and effective method of solving the ice regime problem of the hydropower station,through to join the groundwater of higher temperature to raise the channel water temperature and to prevent the occurrence of ice regime.Simultaneously,the potential energy from the extracted groundwater can be used to offset the power it consumes and even to increase the amount of electricity generated.The channel of Hongshanzui Water Power Station in Xinjiang Manas River Basin was selected as the study area.Using the prototype observation test,flume model tests,numerical simulation and theoretical derivation method to analyze the key factors that pumping well water to melt ice.And studied the process of water temperature change of diversion channel under the condition of pumping well water to melt ice.This study provide scientific theoretical basis and technical support for the channel ice damage prevention and control in the cold region.(1)Taking the Hongshanzui Power Station as the prototype,the observation experiment of the water temperature along the water channel under the operation of the seven wells was carried out.It was found that the water temperature along the channel was 0.5 ~ 2.9?,which was 0.1 ~ 0.3? higher than that before mixed.It was shown that the effect of pumping ice on drainage is remarkable.Simultaneously,according to the method of tank test,24 groups of water tank test were carried out for different channel diversion discharge,different well discharge and different water injection point.The results show that the temperature of channel water rise obviously at the water injection point,and the maximum increase of water temperature can reach 1.6?.The mixed water temperature along the channel is obviously higher than that of the well before the channel,and the better the discharge of the well is more obvious to the warming effect of the channel water.In addition,the three wells at the same time running,so that the channel water produced a cumulative effect of heating,and the effect of water supply to increase the surplus,resulting in excessive waste of heat.Therefore,the rational placement of the water injection point position is particularly important for the actual project operation.(2)The actual operating parameters of the water diversion channel of the Hongshanzui Water Power Station as the boundary conditions.Based on the FLUENT software platform,a three-dimensional mathematical model of water temperature-hydrodynamics was established.A numerical model was proposed to simulate the change process of water temperature of diversion channel under the condition of single well running and Multi-wells running at the same time.The change process of water temperature obtained from the simulation results was compared with prototype observation experiment,and the results indicate that the calculation results were in a good agreement with the prototype observation results.The water temperature change processes of diversion channel were simulated under the conditions of different discharge and temperature of well water,different discharge and temperature of channel water,and different atmospheric temperature.It shows that the mixed water temperature is proportional to the change process of water temperature,different discharges of well and different temperatures of well,and is inversely proportional to different discharges of the channel water.And the mixed water temperature has higher sensitivity to channel water temperature and the discharge of well.At the same time,the multi-well simulation results also show that with the addition of higher temperature well water,each well not only affects the downstream channel water temperature,but also has a certain influence on the upstream water temperature of the channel.According to the actual operation of the project,simulated the channel water temperature of 0.1?,the water temperature changes along the different channel discharge and atmospheric temperature.The results show that with the increase of channel diversion flow and the decrease of atmospheric temperature,the freezing length of molten ice is gradually reduced.Finally,comprehensive analyse the feasibility of the actual project,increasing the amount of well water injection or distributing wells reasonably are the most direct and effective method to improve the channel water temperature and to prevent the operation of the channel in winter.(3)The formula of length of the ice-free water is derived,which is based on the heat balance theory of water flow.And combined the previous prototype observation data to verify the formula of length of the ice-free water,to provide the reliability of the formula.The formula is used to calculate the length of the channel under different hydraulic,thermal and climatic conditions.The results show that: the length of the ice-free water is proportional to the injection amount of well water,well water temperature,atmospheric temperature and daily solar radiation,which is inversely proportional to wind speed,atmospheric saturation and daily snowfall.Among them,the injection amount of well water,air temperature and wind speed have a significant influence on the length of the ice-free water. |
PDF Full Text Request