Study Of Temperature Control Curtain In San Banxi Hydropower Station

Cold water releases in deep water reservoirs have adverse impact on downstream environment and ecology,it is an important issue to eliminate the adverse impact in recent years.Stop log gate intake and multi-level orifice intake are often used to control the temperature of water releases in thermally-stratified reservoirs.However,these measures must be completed before the reservoir running and will cause some power loss.For those reservoirs which have been put into operation without selective withdrawal structures,a temperature control curtain set before intakes has been proposed.The temperature control curtain has many advantages,such as no power loss,no affect the flood discharge,convenient to construct and maintain,low cost,and it can be widely spread.This paper selected SanBanxi hydropower station as our study sample,studied the effect of the temperature curtain on water releases and the force acting on the mooring line.The major study contents and conclusions are as follows.1.A 3-D numerical model simulating the temperature and flow of water near the dam area of SanBanxi reservoir is developed base on FLOW-3D.The model is verified with measured data and be used to analyze the flow characteristics and temperature law of water releases with the effecting of different factor: the water flow formed a mainstream belt under the action of temperature stratification and water releases.The range and velocity of mainstream belt is mainly affected by the flow rate.The temperature of water releases is higher in winter and lower in summer,and increased with the increase of flow rate,decreased with the rise of water level,and is same as the temperature which is between height 409m~440m before the dam.2.This paper verified the temperature control curtain’s validity and analyzed the effect factors using 3-D numerical simulation.The results show that the temperature control curtain can raise the temperature of water releases by the largest 10℃ in the scene that high water level,large temperature gradient and small immersed water depth.The degree of improvement is affected by the type,height of curtain,flow rate and vertical temperature distribution.And then a temperature prediction formula of this scheme is put forward based on above conclusion which is validated by numerical simulation.The results provide basis for the actual operation of the curtain.3.This paper researched on the relationship between force acting on the mooring line and water level,immersed water depth,flow rate releases by means of model experiment.Then the shape variation of curtain and critical flow rate to put down the curtain.The results of this paper would provide technical support for the designing,construction and operation of the temperature control curtain and a new ideas to improve the cold water releases in deep water reservoirs.