Air Pocket Detection in Water and Wastewater Conveyance Pipelines Using Inverse Transient Analysis

Since the presence of air can change the transient responses of pressurized pipe systems, the inverse transient analysis (ITA) may be a feasible approach for detecting entrapped air pockets. In this study, the ITA method was utilized to determine the size of the air pockets at key high points of the system. This was achieved through an optimization process in which the discrepancy between the measured and calculated transient responses (primarily pressure head and/or flow rate) are minimized. Genetic algorithm (GA) was used as the optimization engine. This paper intends to provide preliminary insight with regard to the performance of the ITA in determining entrapped air pocket sizes. The numerical results show that the ITA can capture the size of the air pockets fairly well providing that the number of population used in GA is sufficiently large. Since the number of population increases with increasing number of high points in the system, its application for real pipelines can be encumbered by the impractically long computational time. In such cases the solution is to use a more efficient optimization method and/or to perform parallel computing.