Abstract
ABSTRACT The main objective of this research is the development of a new formulation for calibration of the head loss universal equation friction factor using the Alternative Hydraulic Gradient Iterative Method for calculating the absolute roughness. The method was applied with the aid of Epanet2.dll library for hydraulic simulations in two fictitious distribution networks. The influence of the initial roughness adopted, the number of nodes with known pressure data and position of the nodes with known pressures was tested. To test the influence of the initial roughness to be adopted a computer subroutine has been developed in order to calculate the most appropriate initial roughness for each section. The results showed that it is recommended to use as starting absolute roughness the usual value for the pipe material as new. The developed computational subroutine is recommended for unknown pipes network material or very old networks. How higher number of known pressures in the distribution network, better the accuracy of the method. However, a good layout of the nodes with known pressures was more important than a large number of pressure measurements. The best configuration found to the nodes with known pressures they were separated compared setting together with each other. The method was simple to apply and with good results, and can be applied with a small number of iterations.
Highlights
It is indispensable to use water distribution networks to supply the basic needs of any population, quickly, practicality and comfort for the user of the resource
The results will be presented for the two simulated networks to analyze the nodal pressures found, the absolute roughness of the sections of the networks and the number of iterations required
The calculation of the pressures for both simulated networks, using Equation 11 for the calibration of the friction factor using an initial absolute roughness equal to 0.006 mm, presented satisfactory results, with errors less than 5%
Summary
It is indispensable to use water distribution networks to supply the basic needs of any population, quickly, practicality and comfort for the user of the resource. The service life of a distribution network is considered to vary from 20 to 30 years. Due to the aging of the pipes, their characteristics, as roughness, change, generating difficulties in the analysis, operation and maintenance of the networks. Vasconcelos, Costa and Araújo (2015) report that such modifications can significantly affect the water distribution mechanism, causing losses of internal pressures, loss of fluid transport capacity and even leaks. The difficulty encountered in the analysis of a distribution network isn’t only in the age of the pipes, and in the initial estimation of the parameters or in the data provided by the manufacturers. The difficulty encountered in the analysis of a distribution network isn’t only in the age of the pipes, and in the initial estimation of the parameters or in the data provided by the manufacturers. Cheng and He (2011) argue that without an appropriate estimation of the parameters, a numerical model can not adequately simulate reality, with differences between predicted model and actual systems in the field behaviors
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