| A large area of water field is formed after the impounding period of a newly built reservoir.The water depth in front of the dam becomes deeper and deeper,as the impounding period goes.Underthe a continuous effect of the solar radiation,a stable vertical water temperature stratification structure is formed,and the bottom water temperature below the surface of the water temperature.Using the released lower temperature water for agricultural irrigation continuously will problaly cause the crop loosses and the decrease of spawning rate of aquatic organisms,and do harm to the downstream ecosystem.In order to control the temperature of released water,selective withdrawal is increasingly adopted by the practical engineering.Floating point intake is a typical device taking water from reservoirs for irrigation.Water inlet flow field is closely related to drainage water temperature,advanced study is very necessary if we want to make a further progress on the formation mechanism of the temperature of water released and have a better understanding of it.It is important for the designing and working of selective withdrawal,to study on the formation of water thermal stratification,flow field near the intake and released water temperature systematically.Based on the background of a thermally stratified reservoir,this paper studied on the formation of water thermal stratification and simulated the flow field near the intake and analyzed the flow characteristics near the intake.The main research contents and achievements of this paper include the following aspects:(1)Introduced the formation mechanism of thermal stratified reservoirs,the harm of released lower temperature water,the methods for reducing the negative effect of lower temperature water and the multi-level withdrawal used commonly.Research methods of the formation mechanism of thermal stratified reservoirs and released water temperature are classified and summarized.(2)Based on the FLOW-3D Computational Fluid Dynamics Software,the numerical simulation of the water temperature structure and released water temperature were established and confirmed.We simulated five groups of the intake submerge depth in three defferent withdraw flow rate under four temperature distribution of the reservoir,and analyzed the effect on the flow field due to the temperature stratification,the intake submerge depth and withdraw flow rate,respectively.(3)Based on the existing numerical simulations of water temperature,the water temperature distributions,flow rate,and submerged depth were further analyzed,their sensitivity was further verified. |
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