Study On Mechanism Of Flowing Ice Transport In Ice-Water Two-Phase Water Delivery Channel And Application

China is a country with water shortage and serious spatial and temporal distribution of water resources,especially in the northwestern part of the hinterland of Eurasia.There is dry and less rain,and the water resources are greatly affected by the seasons.The contradiction of water use is more prominent.With the population increase and economic development in Northwest China,the water shortage in some areas is becoming more and more serious,and the long-distance water transfer project is the most direct and effective engineering method to solve the regional water shortage problem.A large number of water transmission projects,taking water supply and power generation as the main targets,was built to ensure the rapid and stable development of the social economy in the northwest of China.However,there are a large number of wide shallow channel projects in Northwest China.At the beginning of the design,the problem of water transport in winter was not considered.With the development of regional social economy,the problem of water shortage in winter has become a bottleneck restricting local development.These wide shallow channel cannot meet the requirements of water transport under the ice cover in the North cold high latitude area,so the ice-water two-phase flow used to realize the winter water in these areas is the key to resource allocation and crack the problem of water shortage during the ice age.Different from the water channel under the ice cover,the ice flowing in the channel with ice-water two-phase flow will be continuously generated and the improper control can easily block the narrow section of the channel.Studying the law of ice formation,evolution and transport along the water in the ice-water two-phase flow channel,proposing the hydraulic control measures that can guarantee the safe water transportation of the channel is of great significance to realize safe water transfer in wide and shallow channel at ice age and give full play to proj ect benefits.In order to prevent the ice disasters during the winter operation when the wide and shallow channels are operated in the ice-water two-phase flow mode,and to ensure the stable and safe operation during the ice age,this paper carries out the following researches:(1)For the problem that the ice is easy to block in the narrow pier section of channel,the experimental sink is used to study the movement law of the model ice in the bridge pier section.By changing the hydraulic parameters such as water flow,water depth and ice shape parameters such as ice size and thickness,the main influencing factors of ice block digging in the cross section of the pier column were analyzed,and the critical hydraulic condition that the ice block can be drained smoothly in the pier section was sought.The experiment showed that the critical Froude number of ice submergence before the sub-section of the pier could be used as a critical condition for the smooth discharge of ice.When the ice size is constant,the larger the thickness-depth ratio t/H(the thickness and depth of the ice floes)is,the larger the critical Fr of the ice block passing through the pier section(hereinafter referred to as Fr);and under the same t/H,the Fr increases first and then decreases with the increase of the plane size of the ice block;The Fr calculation empirical formula was determined by the analytical method.(2)We constructed a one-dimensional ice-hydraulic mathematical model of channel,including water flow model,heat exchange model and ice cover development model,expounded the contents of each model,explained the meaning of the parameters contained in the formula,and briefly explained each calculation method of the model and the preliminary verification of the model showed that the established model can meet the calculation requirements;(3)The water diversion channel of a power station in Xinjiang was taken as an example,using the established one-dimensional channel ice-hydraulic mathematical model to simulate the development law of ice and the characteristics of the situation in the water along the channel in three different typical years of cold winter,flat winter and warm winter.The channel ice conditions influenced by the external temperature conditions,the water intake temperature of the water source reservoir and the impact of the water flow wereanalyzed.The results showed that the ice flow in the channel increases with the increase of the process,and the ice flow at the end of the channel reaches the maximum value;the maximum ice flow in the channel is related to the extreme temperature of winter,but has nothing to do with the average temperature in winter;the higher initial water temperature in the channel is important to reduce the ice flow and alleviate the ice prevention situation;the change of the water flow has little influence on the heat of the channel flow,but increasing the water flow can enhance the flow of ice in the channel;The safe operation of the water two-phase flow channel has certain reference value for realizing the safe water regulation of ice-water two-phase flow and solving the problem of winter water shortage in northwest China.