Numerical investigating of Water Hammer on Optimal Design of Sprinkler Irrigation Network

Optimization and modeling of the pressurized irrigation system in other to reduce their construction cost has attracted many scientists up to the present time. Optimization of these irrigation systems has often been conducted by using available commercial codes or toolbox's of conventional evolutionary algorithms combined with hydraulic models. Developed code that is based on genetic algorithm assigns an integer numeric to each available diameter. Then, by applying the cross-over, mutation and reinsertion with elitism approach on set of chromosomes optimum diameter of pipes are selected. Optimum diameters are sent to another subroutine that has been developed to simulating water hammer pressure in which maximum pressures due to water hammer phenomenon in all pipe are calculated. Then, calculated maximum pressures are sent to optimization subroutine again where constrains of working pressure are substituted by the bursting pressure constrains. Exchange of information between optimization and hammer models continues so that the calculated optimal diameters have not change. The results showed that optimized design by the present model reduces cost of implementation of pipelines of Ismailabad irrigation network from 825935.28$ to 730958.37$ which is equivalent to 11.5% of the cost of implementing of the pipelines.Also the results showed that by changing diameter of 3 pipes of 16 existing pipes we can control excess pressure of water hammer due to rapid closing of all valve at the end of pipelines during less than 1 second. In this case the cost of implementing of the pipelines increases 6.1% e.g. from 730958.37$ to 775511.5$.