Study On Temperature Of Water Released From Thermal Stratified Reservoirs Using Temperature Control Curtains

The large reservoir projects not only bring economic benefits and social benefits,but also bring a series of new ecological environment problems,one of which is to cause the reservoir be typical temperature stratified.The traditional way of water withdraw can not control reservoir withdrawal water temperature,and it brings adverse effects to the ecological environment and crop irrigation of downstream.It is an effective method to control the temperature of withdrawal water using selective withdraw facilities.The experiment on one of the way of selective withdraw facilities——temperature control curtains was conducted in this paper,and the EFDC model is used to simulate the test conditions.The research contents and results of this paper were as followed:(1)It is introduced that reservoir water temperature stratification and formation mechanism,what the effect that the traditional way of water withdraw will bring to downstream,and research progress of reservoir water temperature experiment and numerical simulation.The differences between the temperature control curtains and the other selective withdrawal inlets and the significance of the study of the structure of temperature control curtains were described in this paper.(2)Based on the similarity theory,experiments on temperature of water withdrawn from thermal stratified reservoirs using temperature control curtains were conducted.The experiment results show that the kind of temperature control curtain is primary factor of discharge temperature when water temperature distribution of reservoir is unchanged.When the outlet located on the bottom of the reservoir withdraws,using the curtain allowed water flow from surface only is an effective way to improve the discharge temperature,and when spillway withdraws,using the curtain allowed water flow from bottom only is an effective way to reduce the withdrawal temperature.Based on the two effective ways,the flow rates and the distances of outlet and curtain were added in the experiments.According to the experiments results,the main factors of withdrawn water temperature were analyzed.(3)Based on EFDC model,using the curtain allowed water flow from surface only when the outlet is located on the bottom of the reservoir was simulated,and to compare simulation value and experiment value,the reliability of the model was verified.According to the simulation results the factors of discharge water were analyzed.The simulation results show that when the top of the curtain was deep in the water,the withdrawn water temperature will decrease.Enlarging the flow rates can get more upper water and the withdrawn water temperature will increase.The distance between the outlet and curtain has little effect on the withdrawn water,and when enlarging the distance the time of withdrawn water temperature approaching steady state will increase.