The purpose of this study is to investigate the problems resulting from unsteady flow, in irrigation pipelines
networks; due to pump power failure and provides the necessary control devices, to analyze transient flow under
all possible operational conditions. The present investigation emphasized on the unsteady flow cases on the
problem of pump power failure. In this case, protecting the irrigation pipelines networks against water hammer
is of great importance. A hydraulic model is developed to study the transient flow problems. It is prepared
considering several boundary conditions to define the irrigation pipelines networks. Therefore, this study aims
to investigate the effect of using a protection device; an air vessel; on the network. Otherwise Comparison of
protected case using an air vessel and using an air vessel with two surge towers as protection devices. Subjects
to evaluate and optimize a hydraulic design are economy, safety and control principles to make an effective and
efficient system. Through this work, a parametric study is applied using Water Hammer Software Wanda V3.03.
Irrigation pipelines networks can be simulated with this water hammer model. The method of characteristics based
solver can be interrupted and resumed during a simulation.This program developed and has validated
against many experimental measurements (WL/Delft Hydraulics (2006). The program is available at the
Hydraulics Research Institute (HRI), National Water Research Center, Egypt. The results of the study,
graphically presented for the various operating conditions. The results include the relationships of discharge,
capitation volume; head and pressure verses locations for the different cases. Also include the relationships of
discharge, pump speed verses time histories. In this study, the results show that using the proposedan air vessel
as a protection device proved to be effective for prevent column separation , using of air vessel with two surge
towers are becoming more effective and decrease the size of the initial air vessel. The results show that
increasing of diameter of pipes decreases the magnitude of the maximum pressure heads in the resulting water
hammer pressure but does not prevent column separation. Otherwise, change of pipe material type from GRP to
steel decreases the maximum pressure but does not prevent column separation. Finally, it was found that
increasing the polar moment of inertia of the pump does not decrease the maximum pressure or the initial air
vessel volume. |
