NUMERICAL ANALYSIS OF HYDRAULIC TRANSIENTS IN PIPELINE SYSTEMS WITH VARYING BOUNDARY CONDITION USING LAPLACE TRANSFORMATIONS AND FREQUENCY DOMAIN METHOD

Abstract

This paper foucs on the different between the analytical solution for the variation in hydraulic grade line (HGL). Basic fluid equations solved either, in the time domain, using classical method of charectaristics (MOC) and compare the results with Laplace transformations method and Frequency domain method. The main diffrence between these methods are, the Frequency domain method depends in the analytical solution on the Fourier series approach, but this approach is not well suiet to the case where the boundary conditions vary during the transient event. A Laplace transform solutoin approach overcomes this difficulity accordingly, the results for the pipeline system having varing demand showen that the Laplace transformation sense to wave pressure accur due to suddenly change in flow rate eather than Frequency domain method. By applying these method firstly on assumed network having suddenly chang in flowrate, then applied the mathematical model on Al-Razaza pumping station that suffers from transient flow due to suddenly change in pumping rate, and assumed this practical application to this study. Normalized hypebolic governing equations for apressur transient in a pipeline with change in demand are derived, where the discontinuity induced by a variations in demand by using a delta function. The effects of the change in demand on pipeline system transients induced by a pulse boundary perturbation and continuously changing boundary perturbation are invistigated in detail.