Modeling of Transient Flow Under Superposed Singularities: The Leak and the Junction

In this research paper a new numerical model is developed to predict the leakage effect occurring at a pipeline junction. This model is based on the characteristic method. The two hydraulic singularities (leakage and junction) are taken as superposed boundary conditions that are located in the same section. This study allows locating a leak by separating its effect on the temporal pressure history from that of the junction. A numerical test based on different formulae shows the interest of a new approach for detecting and sizing a leak. The method uses transient pressure waves initiated by the sudden closure of a downstream shut-off valve. The effect of the leakage and pipe-geometrical-characteristics-change at the junction of two lines are separated and a new procedure of locating and sizing the leak is also investigated in the case of shrinkage. The shrinkage causes a pressure increase but the leak signature appears on the pressure time evolution as pressure drop. This finding facilitates the distinction between the effects of the two superposed singularities on pressure history. The friction is neglected to calculate the leak location and size. The sensitivity analysis either in sizing or locating leak is investigated to select the suitable formula.