Simulação computacional do fluxo induzido por vazamentos de água em tubulações

Abstract

The 2021 IPCC (Intergovernmental Panel on Climate Change) report indicates changes in water quantity and seasonality due to climate change and reports that approximately 80% of the world's population already suffers from high levels of threat to water security. Given the vulnerability of water resources and the role of climate change in intensifying adverse impacts on human societies, it can be said that there is a great demand for studies on the detection and quantification of losses in water supply and distribution systems. In this context, the general objective of this research was to evaluate the impact of geometric, hydraulic, and hydrodynamic factors on water leaks in pipes through computational fluid dynamics (CFD). For that, the ANSYS FLUENT software was used. The calibration and validation of the tested mathematical models were performed based on experimental data considering different pressure and velocity boundary conditions, with pipes of three diameters (DN25, DN 50 and DN 100). The results showed that the RANS turbulence models (k-ε e k-ω SST) can reproduce well the phenomenon of leaks in water pipes, presenting a maximum deviation of 8% compared to the discharge coefficient (Cd) obtained experimentally. The results further indicated that the variation of Cd as a function of orifice diameter and shape can be attributed to the effect of tube curvature on the flow convergence through the orifice. Empirical correlations and those from simulations explaining Cd through dimensionless coefficients (d/D, ΔH/D, Re) presented a high R-squared value (95.01% and 79.08%, respectively). The application of these correlations in five water mains in Ceará indicated that the traditional use of Cd as a constant can lead to errors in the quantification of losses, and consequently mistakes in decision making.