José Carrillo

Complementary Methods for Determining the Sedimentation and Flushing in a Reservoir

AbstractThis study analyzes the changes expected in the Paute River in Ecuador as a result of the future construction of the Paute-Cardenillo Dam (owned by Celec Ep-Hidropaute). The project must remain in use throughout its projected useful life. For this reason, the operational rules at the reservoir need to consider sedimentation effects. Four complementary methods are used to study the sediment transport and flushing. Empirical formulas and one-dimentional (1D) simulations are used to estimate sedimentation in the reservoir. Two-dimensional simulations allow the analysis of a 72-h flushing operation in the reservoir. Three-dimensional simulations show the detail of the sediment transport through bottom outlets, where the effect of increasing the roughness due to the sediment transport in the bottom outlets is considered. The results demonstrate the utility of crossing different methods to achieve adequate resolution in the calculation of sedimentation and flushing operation in reservoirs.

Plunge pool dynamic pressures: a temporal analysis in the nappe flow case

ABSTRACT Rectangular jet, or nappe flow, constitutes one of the energy dissipation methods used in the overtopping of dams. This paper reports new laboratory data on pressures, velocities and air entrainment and analyses the degree of break-up of a rectangular jet before entering the basin and the pressure fluctuations on the bottom of the pool. It is found that the maximum mean dynamic pressure coefficient of 0.86, which is valid for circular jets, is reduced to 0.83 for a rectangular jet. The study has also led to a relationship between the fluctuating pressure coefficient and the degree of the jet break-up. The peak pressure coefficient occurred for break-up length ratios (i.e. falling height/length) in the range of 1.00–1.20. The scaling effects are negligible for scales less than 1:10. The new set of characteristics given in the paper fills the current knowledge gap related to rectangular jets.

Comparison of clear water flow and sediment flow through bottom racks using some lab measurements and CFD methodology

Bottom water intake systems consist of a rack located on the stream bed, so that water passes through the rack to be collected. These structures are used in small mountain rivers with steep slopes and irregular riverbeds, in which intense sediment transport and flood flow are found. These racks are designed to derive as much water as possible with the minimum retention of solids. Some attention has been given to the occlusion of racks due to the deposition of debris over them or to the quantity of sediment that gets into the rack and is transported along the derivation channel. Nowadays what we want is to optimize this kind of intake to use them in discontinuous and torrential streams with a high concentration of sediment. The methodology of Computational Fluid Dynamics (CFD), which is based on numerical solution of the Reynolds Averaged Navier-Stokes (RANS) equations together with turbulence models of different degrees of complexity, simulates the interaction between different fluids, such as the sediment-water two-phase flows that appear in intake systems. This paper compares the main results obtained in clear water flow and sediment flow through a rack, using some laboratory results and CFD methodology.

Intake Systems In Ephemeral Rivers

This paper is focused on the study of bottom rack intake systems located in ephemeral and torrential streams. Clear water, and water with gravel sediment transport have been analyzed. Different tests have been carried out to quantify the influence of the solids passing through the racks. The wetted rack lengths and the efficiency of racks are studied. The clear water has also been modelled with computational fluid dynamics, and compared with the measurements obtained in the laboratory. Experimental and numerical studies that characterize both the clear water and the influence of solid load in the operation of the bottom racks will allow us to improve the existing design criteria.

Comparison of PIV measurements and CFD simulations of the velocity field over bottom racks

In this work, the comparison of the velocity field over a bottom rack system measured by Particle Image Velocimetry (PIV) and simulated with numerical simulations (ANSYS CFX v14.0) is presented. Laboratory measurements are taken in a physical device located in the Laboratory of Hydraulic Engineering of the Universidad Politécnica de Cartagena (Spain). Velocity and pressure coefficients of the energy equation are obtained and used to evaluate the water profile along the racks. Pressure distribution along the flow depth is presented for several distances along the rack. Pressure results are compared with the pressure deviation terms from hydrostatic pressure profile proposed by several authors.