Simulation And Evaluation Of Leakage Characteristics Of Urban Water Supply Network

The year of 2020,as the decisive year when the loss rate of urban water supply network reaches the standard,which poses a severe challenge to the water department.As a universal macroscopic evaluation index,the leakage rate is widely used by local governments and water departments.However,with the acceleration of urbanization,the water consumption of residents is gradually increasing,which seriously affects the accuracy of the leakage rate and other evaluation indexes.How to select appropriate indicators according to the actual situation has become a difficulty in the control of leakage.Therefore,it is urgent to analyze the applicability of each index and define their respective application scope,so as to speed up the adoption of leakage control measures and avoid the continuous leakage of leakage points.In this paper,based on the consistent leakage model,multi-leakage condition simulation is carried out by a numerical simulation of the pipe network structures as example,and the relationship between pipe network leakage flow and pipe network inlet pressure,the most unfavorable point pressure and the average pressure is respectively studied in the presence of multi-leakage points.By reducing the pipe network pressure and changing the number of leakage points,the stability and influencing factors of the pipe network leakage relationship were explored.The results show that no matter under which pressure value,the leakage of pipe network is exponential with the pressure.The goodness of fit is higher than 0.99 except that individual conditions the leakage index of which is 0.5.Therefore,the leakage can be calculated according to the actual pipe network pressure data and instantaneous flow data.The variation of pipe network inlet pressure and the number of leakage points did not affect the exponential relationship.By using correlation analysis and regression analysis,the relationship between pipe network leakage model and leakage model of points were established on the premise of the changes of the inlet pressure and the number of leakage points,which provided a method for the determination of the number of leakage points and the estimation of the leakage amount after pressure reduction.Under the circumstances of the water demand changes,network expansion or the pressure regulation,the application of leakage rate,water leakage per unit length,water leakage per unit area,leakage model of pipe network and ILI were analyzed,respectively.That could improve accuracy and pertinence of leakage estimation.The results show that the leakage rate,the water leakage per unit pipe length and the per unit area can be used as the leakage evaluation indexes when the water demand fluctuates in the range of 10%.When the change of water demand is higher than 10%,the water leakage per unit pipe length and water leakage per unit area can further weaken the impact of water demand on the evaluation of leakage,which is suitable as the evaluation index of water leakage.After the expansion of the pipe network,it is more appropriate to use the water leakage as the evaluation index.In the step-by-step pressure adjustment process of pipe network,the water leakage per unit pipe length,water leakage per unit area and the pressure difference between the most unfavorable point before and after the pressure reduction can be used as the evaluation index.Combined with the practical engineering case,the mobile regulator is used for the first time to realize stable pressure regulation of the pipe network.Based on the method of minimum night flow,the statistical method is used to determine the pipe network leakage flow at night and solve the leakage index model of pipe network.On this basis,analyzed the change of leakage state of pipe network in the recent 5 months.And the equivalent leakage water supply number index is proposed to be used for leakage evaluation,which takes into account the factors affecting users’ water consumption and is more stable than other indexes,and is suitable for leakage state evaluation under the changes of pipe network operation state.The acquisition and analysis of field measured data can provide reference for other pipe network leakage evaluation.