Study On The Error Analysis Of Full-featured Pump Curve And Impact Of Water Hammer Calculation

With the rapid development of long-distance water supply project and the frequent occurrence of pipeline explosion, calculation and protection of water hammer analysis also has been emphasized by engineering technical person. In the many ways of water hammer calculation, the electric method-characteristic line method is one most common method which is applicated in recent years. Its basis is also the basic equations of water hammer, which is conversed into the ease computing finite difference equations by means of characteristic line. In the analysis and the calculation of water hammer, the study of Full-featured Pump Curve is very important.In this paper we studied the error analysis of Full-featured Pump Curve and impact of pump-off water hammer calculation under the specific data Ns=80,127 and 333. At last we combined a large number of engineering examples and have a comprehensive analysis and calculation. The main working are as follows:(1) We elaborated the meaning of the Full-featured Pump Curve and the application of pump-off water hammer calculation in detail. Mainly introduced the discrete data of the Full-featured Pump Curve value under the specific data Ns=80,127 and 333. Large amounts of data, including the maximum, minimum and the theoretical value of the Full-featured Pump Curve, are got by picturing and calculating.(2) As specific data Ns=80,127 and 333 of the pump for example, we used large amounts of data and the Full-featured Pump Curve discrete data values to analyze the absolute error and relative error. By the error analysis of Full-featured Pump Curve found that relative error is large which have impact on the calculation of pump-off water hammer.(3) As the three pumping stations of Yanchuan water diversion project, one pumping station of Fuxin water supply project in Liaoning Province, five pumping stations of Yanchuan water diversion project, pumping station of Jilin Province water supply project, pumping station of Liaoning Province water supply project for example, the maximum, minimum, and theoretical values of Full-featured Pump Curve under Ns=80,127 and 333 were substituted into the program, which were calculated under the same conditions. Combined with the maximum head of the pump envelope, we analyzed the impact of pump-off water hammer step on the error of Full-featured Pump Curve, the final conclusion are as follows:①The error of Full-featured Pump Curve have a greater impact on pump-off water hammer, especially impact on the large diameter, high lift pipeline. ②The error of Full-featured Pump Curve have a greater impact on pump-off water hammer, especially impact on the pipeline near the pump which lead that it has great water flow fluctuations in a very short period of time.③The error of Full-featured Pump Curve have little impact on the minimum pressure value of pump-off water hammer.④The effect of Full-featured pump Curve error on pump-off water hammer are also relatedand with water hammer wave velocity of the pipe.⑤In order to avoid the uncertain effect of the error of Full-featured Pump Curve calculation results, please try to use the theoretical value of the Full-featured Pump Curve to have the pump-off water hammer calculation.