Hydralic Property Of Resistence Elements In Water Systerm Of City

An efficient approach improving the draggling actuality of water supply industry management level in our country is to establish the water supply network model and optimization dispatching system. But there are several difficulties when modeling the water supply network, such as no enough databases, un-detailed main parameter of important resistance elements et al. The research is proposed based on the above background.Resistance elements of water system in this article means that of water supply network.Broadly saying, resistance elements of water system consist of pipes,valves,pool, cistern defined as positive resistance elements,and pump defined as negative resistance elements.This article mostly researches pipes and valves'hydralic property and calculation whose parameters are of great importance in modelling.The coefficient of C in Hazen-Williams formula,naemd resistant coefficient of pipe too,indicate the hydralic property of water pipe,and is an important control parameter in water supply network,whose value derectly effect the precision of water supply network.The author found that invalid data from the first test in street of harbin took some percent.We summarized the shortage of the test,improved the equipment. Then,after we tested again,the result showed that the invalid data decreased much,and the result increased precision and scientific at the same time.The article analysed nine results about the tested pipe ,then proposed equivalent pipe.And we found that in all modelsdescribing pipes'equivalent pipe and used years'relationship,linear model gived the best result.and therefore the author inferred when used years increasd ,the pipe's equivalent pipe declined linearly.In actual water network, valve can be seen as dummy pipe.Also we can put pipe and valve as dummy valves. Dummy valves'flux adjusting ability depend on the weight actual valve compared to dummy valves.On the base of testing valves , we established the maths model about the relative opening degree of DN150 valve and its partial resistant coefficient;and therfore based on it,we derived maths model about relative opening degree and flux ratio ,plus that with flux adjusting intensity.The model of relative opening degree and partial resistant coefficient is the most key to study other hydralic target.Model about relative opening degree and flux ratio takes great importance to certain valves such as reductor valve.The curve describing relation between relative opening degree and flux ratio reflect more widely copmared with the model between relative opening degree and relative flux. The curve describing relation between relative opening degree and ralative flux reflect only under the condition at experiment,especaiily the press.However, flux ratio reflect all-side,it Indicate all conditions.In the outdoor testing,the author used Pitot pipe to get the average velocity of flow,basing on the theory of one-point method,and finally reliased the suceessful test without stopping the supply of water,.So we get the partial resistant coefficient,which is a landmark in actual testing.Testing velocity of flow using Pitot pipe is simple, economy, accurate, scientific.compared with ultrasonic flowmeter, ultrasonic flowmeter is prone to be effected by electromagnetism,and ultrasonic flowmeter, can only detect the homosphere pipe with less growth ring. Pitot pipe can be used more widely.When street and pipe and test means in resistant coefficient of pipes testing has been decided,the author suggest that to give valve resistence test on the vavle which should be turn on or off in pipe testing,before resistant coefficient of pipes testing.For this,we can know the hydralic adjust propertyof the valve which shall be turn on or off in resistant coefficient of pipes testing.From that,we can decide the range to turn on or off,which can escape testing in bad hydralic areas to improve precision of the reslut.So at the same time we saved much time in turn on or off the valve and saved flow too.