Investigation of Transient Flow Field Data in Water Transmission Mains Using Bentley Hammer Software (Case Study)

Water transmission systems consist of storage reservoirs, pumping stations and pipelines. Pump station power failure, opening and closing of control valves and pipe rupture because transient conditions in pipelines. Transient flow principal equations such as momentum and continuity equations are mainly analyzed by the method of characteristics using engineering software and under boundary conditions. In this study, friction head losses were calculated by Bentley Hammer software under steady, quasi steady, unsteady and unsteady-Vitkovsky states and the results were compared. In Piranshahr water transmission system, the pressure changes were measured using a rapid and sensitive pressure indicator at the pumping station and under critical conditions of electricity power failure. Field data were compared to the Bentley Hammer output data using statistical methods. A comparison between the two, demonstrated the correspondence of time periods. Under unsteady-Vitkovsky method, the mean absolute errors were 5.13 and 5.45 mH2o for the initial stages and full period of data logging, respectively. For the maximum pressures values, the maximum difference was observed in the unsteady method (-14.62 mH2o) and the least values were associated with the steady and quasi steady method (-4.58 and -4.56m H2o respectively). As for the minimum pressures, the steady method yielded the highest (-5.55 mH2o) and the unsteady method the lowest difference (-1.52 mH2o). Increasing and decreasing the wave speed directly affected the maximum pressures while having an inverse impact on the minimum values. Based on the results of this study, the use of unsteady-Vitkovsky method in. Hydraulic modeling is recommnded