Author(s): Celia Ortega Flores; Alejandro Carrasco Minguez; Antonio Lastra De La Rubia; Patricia Gomez-Martinez

Linked Author(s): Antonio Lastra de la Rubia

Keywords: Hydraulic transients; Pressure surge monitoring; Hydraulic network management; Waterhammer mitigation; Pump stations

Abstract: Waterhammer in pumping systems is an issue of concern to stakeholders, especially with regard to events resulting from accidental changes in operation, such as unplanned shutdowns due to electrical failure or human error. The transient response of these eventualities can be predicted by means of computer modeling with commercial waterhammer softwares. In existing structures, accurate calibration of these models relies on the existence of extensive field data, for which high frequency transient monitoring is required. Against this background, R&D+I department of Canal de Isabel II is developing a project for transient analysis in several pumping stations. In each of these installations, field tests are performed. These consist, either in registering daily activity of pumping stations or in programming specific starting/stopping sequences. For data collection, high frequency dataloggers are placed both along the network. These instruments are capable of monitoring rapid pressure changes by means of a highly pressure transducer (range 0-30 bar) and the recording up to 100 measurements per second. Hydraulic dynamic models were implemented using a waterhammer specialized software based on the geometric and operational data of the pumping station and hydraulic network. This computer tool uses the method of characteristics to solve the mass and quantity of motion balances inherent in the elastic model. As stated, the reliability of the numerical model for the analysis of hydraulic transients under unforeseen circumstances is given by the calibration process, through which parameters and boundary conditions are modified to ensure that the results corresponding to standard operations conform to the records obtained in the monitoring campaigns. Subsequently, once this target is achieved, different mitigation solutions are considered to evaluate its effectiveness concerning the attenuation of peak (minimum and maximum) pressure values. Furthermore, apart from addressing the simulation of specific pumping systems, the research comprises the implementation of a database that cross-checks the different features and geometric characteristics of the case studies analyzed with a wide range of operating solutions and design recommendations related to surge control. To reach this goal, a collection of simplified, synthetic waterhammer models was elaborated based on those accomplished for particular cases studied. Pipework materials and diameters, operating conditions of the pumps, profile geometry, and several other properties were modified in order to elaborate a test bench for performing a sensitivity study to evaluate the effectiveness of surge protective measures. Among others, the implementation of surge vessels and tanks, retention and relief valves, modification of pump operating set points and types of start-ups and trips, including the use of soft starters and frequency variators, were trialed. Study enables the standardization of guidelines for mitigating surge effects in pumping stations, as well as the possibility of establishing design recommendations and good practice operations.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022875

Year: 2022