Author(s): Jorge Reyes; Brayand Mendoza

Linked Author(s): Jorge Reyes

Keywords: Poechos Reservoir; Sky jump; Sink; Erosion; Ansys CFX

Abstract: The Poechos Reservoir is the largest hydraulic work in Peru. It is located in the riverbed of the Chira River, specifically, 40 km northeast of the city of Sullana in the department of Piura. It serves as a regulator of large avenues and supplies irrigation to the Chira and Piura valleys. Among the structures that the reservoir has, there is a spillway with three radial gates, which allow the exit of a maximum flow of 5400 m3/ s. The flow is transferred and delivered downstream through a ski jump to a dissipation pool. However, the flow impacts on a hill located in front, preventing a direct exit of the fluid towards the channel of the Chira River. This recirculates the flow in the dissipation pool and consequently generates erosion in the vicinity of the foundation of the dam. In the present work, a numerical model has been developed, both of the ski jump and the dissipation pool, with the Ansys CFX program, which is a three-dimensional fluid dynamics software. The software has great fidelity, and it is capable of simulating and reproducing the fluid flow phenomena described in the previous paragraph. Numerical models in general, and therefore the one developed in this study, have certain stages that are elaborated step by step, which are: the definition of the problem, the preprocessing that includes the modeling of the geometry, the meshing and the configuration of the model, the solver and the post processing. In this last step the results of the variables of interest are displayed. It is important that the model has an adequate discretization of the domain, since this will determine its convergence and therefore reliable results will be obtained. The results obtained from the modeling are very close to those obtained in field measurements. Through calculations, these show speeds of up to 2.1 m / s located in the vicinity of the reservoir foundation. Consequently, it is concluded that erosion exists, since the surface of the dissipation pool is made up of sand, a material that does not resist the speeds that are generated. With the results of the modeling it has been possible to determine the alternative solution to the erosion problem.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221716

Year: 2022