Analysis and Comparison of the Behavior in Spillway of Exceedances and Stilling Basin of Sabana Yegua Dam using Numerical Model in ANSYS with Physical Model

The dam of Sabana Yegua, located in the province of Azua in the Dominican Republic, had a spillway of exceedances, which was not capable of evacuating the extraordinary flows due to the presence of natural events such as hurricanes, which were not considered in its initial design. It needs to be complemented with the design and construction of a second spillway with its respective stilling basin, which will prevent possible massive erosions in the structure, dissipate the kinetic energy of the flow, control the great velocities in the Yaque del Sur riverbed, avoiding the future floods in nearby areas.

The present study has as general objective to analyze and compare the behavior of the flow in the second spillway of exceedances and stilling basin of the Sabana Yegua Dam, using a numerical model developed in Ansys CFX and its respective physical model.

To achieve this general objective, it is proposed to develop the following specific objectives:

• Model numerically the behavior of the flow of the second spillway of exceedances with two types of stilling basins using Ansys CFX. The complete modeled structure consists of four parts: an approach channel, chute with variable slope, stilling basin and an exit channel. The flows to be evaluated will be: 85, 220, 500, 1144, 2318 and 3342 m³/s.
• Model the behavior of the flow in the variable slope chute considering two specific cases: without and with aerators.

The expected results of the research will show the comparison between the results of the numerical model in Ansys CFX with those obtained in the physical model of the Sabana Yegua Dam built in the Institute of Hydraulics, Hydrology and Sanitary Engineering of the University of Piura (Peru), and thus obtain a correlation coefficient between the numerical and physical model for supercritical flows with Froude number between 1 to 4, with the intention of determining the percentage of variation between the results that the software will show in flows with Froude greater than 1 with the physically collected; this will be considered because Ansys CFX has certain deviations in the calculation in supercritical flows compared to real values.

Another result will be to obtain and compare the shear forces, velocities and current lines at the bottom of the structure of the chute considering the use of aerators and without the use of these and determine the importance of these in the hydraulic design.