Experimental Study On The Water Temperature At A Multi-Level Intake Structure Of Hydropower Station

Water has the obvious character of temperature-stratified phenomena along with the depth in large reservoirs,which could vary considerably to 20℃from surface to bottom.Along with the importance to environmental protection,a Multi-Level Intake Structure(MLIS)has been gradually introducing in heavy hydropower station.As the relief measures of discharging cold water,the purpose of MLIS is to stretch selectively different layers of water,and reduce the negative effect of releasing cold water on downstream environment.Currently,the analog experience and numerical simulation has been widely used to research such subject at home and abroad.However,the model test on it has been very few.Therefore,it is necessary to study the discharged water temperature of MLIS by the model test.Based on Nuozhadu Hydropower Station in this paper,the discharged water temperature of MLIS by the model test to discuss the relationship between the water temperature distribution,the water intake location and the temperature of discharged water.The main conclusions are summarized as follows:1.The water temperature distribution of the typical level of years in the reservoir area based on Nuozhadu Hydropower Station is well simulated experimentally.When achieving the target elevation,water temperature can be stably stratificated in the model,and simulated very well with the goal of temperature.The temperature on the same elevation of the section is basically the same.Each layer of the water is stable and mixed less.2.When the intake works,each layer of the water had no significant changes in water temperature regardless of 2.58 m from the intake section or 6.5 m from the intake section.Water temperature increased obviously and quickly achieve stability at intake point downstream.According to the distribution of water temperature in the reservoir area and the measurement on the discharged water temperature under different conditions,we can see that the discharged water at the intake point is mainly from a certain height above the stoplogs gate roof.The height is related to the operation of the stoplogs gate,the water temperature distribution in the reservoir, working elevation and the discharged flow.3.Stoplogs gate with intake in layer can be used to raise the temperature of discharged water effectively,and reduce the negative effect of releasing cold water on downstream environment.The reasonableness of stoplogs gate with intake in layer is demonstrated on the angle of increasing the temperature of discharged water in this paper.