Calculation And Investigation About Theory Of Water Hammer

This paper, firstly, presents briefly the basic theories of current water hammer calculation including both water hammer mathematic model and calculative methods; points out continuity equation not meeting the conditions of steady flow, sin 0 being inherent illogically in current water hammer mathematic model, calculative methods of the equation being scarcely precise, etc, which account for the continuity equation is false in the current water hammer mathematic model. Secondly, detailedly analyzing reasons inducing these problems, author finds it is that not thinking of the slope of pipeline and the friction in the process of producing water hammer pressure functions, but, thinking of the effect of the slope of pipeline in the process of producing the consequent water hammer calculative continuity function, which results in the inconsequent illogicality in the whole process of producing. It is the fundamental reason that the continuity function faults.The paper uses precise step to produce the continuity function of water hammer mathematic model, not only gains more precise water hammer pressure function and water hammer wave speed functionbut also founds correct water hammer mathematic modelContinuity EquationMovement EquationAfter ignoring subordinate facts, function (1) and (2) translate into the current applied water hammer pressure function and water hammer wave speed function.The new water hammer mathematic model (3) fully meets the conditions of steadyflow.The other primary part is that based on the correct water hammer mathematic model (3), applying character line method, to translate the differential equation group (3) into character equation group, to count the character equation integral along with character line and at the same time to substitute the integral form for the difference form so as to make use of computer to carry through numerical value calculation of the water hammer pressure. The paper , too, does with the corresponding argumentation of all kinds of boundary conditions. The above content improves the no preciseness of disposing of the character line method of current water hammer calculation, namely translates " ds/g=+adt/g multiplies the character equation" into "ds/g = (v+a)dt/g multiplies the character equation". This no preciseness not only influence the calculative precision but also badly induces the character difference equation not meeting the conditions of steady flow.Corresponding to the correct water hammer mathematic model (3), the character difference equation isBy comparing the new mathematic model with the old mathematic model, the last calculative part of paper argues the falseness of the current water hammer mathematic model, makes use of the improved character line method to analyze the correct mathematic model (3), studies all kinds of facts' impact on water hammer pressure value and water hammer phenomenon attenuation, points out that, in the long pipeline system, the subarea calculation of head loss along with flow rather influences the calculative results of water hammer pressure, advices to take the subarea calculation of head loss along with flow into account in the water hammer calculation of the long pipeline system. Ulteriorly, considering the local head loss in inlet opening and pipes junction plays more important role in the calculative results of water hammer pressure calculation of the short pipeline system. At last, considering the running trait of hydraulic turbine in true power stations, combining the complex pipe line system, generating electricity, discharge flood all use of Pan Shi Tou reservoir compute the unsteady transition process.