Numeric Modeling of Water Mains Filling Considering Air Pressurization
The filling of water mains represents a type of unsteady, two phase flow that normally follows maintenance procedures which require emptying the mains. This is performed carefully to avoid the formation of air pockets, which can cause high pressures in conduits and also reduce their conveyance capacity. Numerical modeling is an essential tool for the study of this kind of problem as a means of anticipating operational issues. Among the models proposed for this application are those of Liou and Hunt (1996), Izquierdo et al. (1999) and Vasconcelos (2007). Such models’ applicability is limited due to the assumptions made in their development, which include simplified shapes of water filling fronts, and non-consideration of ventilation systems or air pressurization effects. This chapter will present a numerical model for the simulation of gradual water mains filling that allows for both a more realistic inflow front and the development of air pressurization. The model solves a system of ordinary differential equations which represent the advance of the inflow front, the development of air pressurization, and conservation of the air phase. The model uses Object Pascal and has a friendly and interactive user interface, and future tests will present a comparison between model predictions and laboratory measurements.
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