Numerical modeling of air-water interaction in bottom outlets. Application to susqueda dam

Abstract

The convenience of installing an aeration system in dam bottom outlets is well known nowadays. Otherwise, damages due to cavitation and vibration are frequently serious, as could be observed in several dams built in the beginning of the 20 th century. Several empirical formulas have been developed for calculating the maximum air demand, but their results are very sensitive to the variation of the geometrical characteristics of the installation. The Ministry of Science and Innovation of Spain has funded a project to address this problem using numerical modeling. The interaction of two fluids (air and water) with very different physical characteristics is the greatest difficulty to be overcome. To deal with this challenge, the Particle Finite Element Method (PFEM) has been used. The method has being applied to verify the performance of the new flat-seat circular-section valves, which design is being developed by INHISA as an alternative to the traditional Bureau-Type. Firstly, a case comprising the mentioned valve in a standard facility was analyzed for validation purposes, as well as for studying the influence of the different parameters in the air flow. Then, the method has been used for the analysis of the performance of the bottom outlets of Susqueda Dam.