Papers by José Germán Rodríguez Carrillo
The study analyzes the expected changes in the Paute River in Ecuador as a result of the construc... more The study analyzes the expected changes in the Paute River in Ecuador as a result of the construction of the Paute-Cardenillo Dam (owned by Celec Ep-Hidropaute). This dam will integrate the National Electric System of Ecuador with a total electricity installed capacity of 600 MW which will produce 13000 GWh per year. Given that the project must remain viable throughout its useful life, the operational rules at the reservoir are required to include sedimentation effects. Sediment transport and flushing are studied by using four complementary procedures: empirical formulae, one-dimensional simulations (time required for sediment level reaches the height of the bottom outlets), two-dimensional simulations (flushing) and three-dimensional simulations (detail of the sediment transport through bottom outlet). MAIN CHARACTERISTICS OF THE PROJECT The study zone is situated in the Paute River basin in Ecuador to 23 km downstream from the Amaluza Dam. The area to be analyzed is of 275 km 2 of...
The increasing of the magnitude of design floods has prompted the re-evaluations of spillway capa... more The increasing of the magnitude of design floods has prompted the re-evaluations of spillway capacity and the operational scenarios for large dams throughout the world. Current capacity of many spillways is inadequate and dams might be overtopped during extreme events. New loading for the dam and questions about erosion and scour downstream from the dam are necessary. In this way we need to estimate the hydrodynamic actions on the dam bottom or the basin where the jet discharges, as a function of the characteristics of the jet. So the pressure and velocity distributions of the flow in the plunge pool must be estimated to evaluate potential scour that might destabilize the dam. The high turbulence and aeration phenomena that appear in falling jets and dissipation basins make it difficult to carry out studies based only on classical methodologies. This work addresses overtopping flows, and compares numerical results against our own experiments. Instantaneous pressures, velocities and ...
Hidr@m Group, Universidad Politécnica de Cartagena, Cartagena, Spain, [email protected] The s... more Hidr@m Group, Universidad Politécnica de Cartagena, Cartagena, Spain, [email protected] The study analyzes the expected changes in the Paute River, located in Ecuador, as a result of the construction of the Paute-Cardenillo Dam. To evaluate the stability and safety of the structure, it is necessary to ascertain the shape and dimensions of the scour generated downstream. The scour is studied with three complementary procedures: empirical formulae obtained in models and prototypes, semi-empirical methodology based on pressure fluctuations-erodibility index and computational fluid dynamics (CFD) simulations. A preexcavated stilling basin is proposed and analyzed.
When dam overtopping produces rectangular free jets that discharge into plunge pool basins below ... more When dam overtopping produces rectangular free jets that discharge into plunge pool basins below the dam, the pressure and velocity distributions of the flow in the plunge pool must be estimated to evaluate potential scour that might destabilize the dam. The high turbulence and aeration phenomena that appear in falling jets and dissipation basins make it difficult to carry out studies based only on classical methodologies. This work addresses plunge pool flows, and compares numerical results against our own experiments. Instantaneous pressures, velocities and air entrainment were obtained with the use of piezoresistive transducers, Acoustic Doppler Velocimeter and optical fiber, respectively. Mean velocity field and turbulence kinetic energy profiles were determined. To identify the level of reliability of models, numerical simulations were carried out by using the “homogeneous” model of ANSYS CFX, together with different turbulence closures. The numerical results fall fairly close ...
En esta conferencia presentamos resultados de una investigacion desarrollada dentro del Plan de M... more En esta conferencia presentamos resultados de una investigacion desarrollada dentro del Plan de Mejoramiento Institucional de una universidad en Chile. Buscamos caracterizar y comprender el conocimiento del profesor de los numeros racionales como objeto de aprendizaje, uno de los subdominios del modelo Mathematics Teachers’ Specialized Knowledge (MTSK) en el caso de una profesora de matematicas de la ensenanza media chilena, a traves de observaciones de aula, cuestionarios y entrevista. Los resultados permiten identificar las necesidades formativas de los profesores y concluir con algunas reflexiones para mejorar la formacion inicial de los profesores de matematicas
Hydraulic jump is one of the most extended and effective mechanism for hydraulic energy dissipati... more Hydraulic jump is one of the most extended and effective mechanism for hydraulic energy dissipation. Usually, hydraulic jump characteristics have been studied through physical models. Nowadays, computational fluid dynamics (CFD) are an important tool that can help to analyze and to understand complex phenomena that involve high turbulence and air entrainment cases. Free and submerged hydraulic jumps are studied in a rectangular channel downstream a sluice gate. Velocity measurements are carried out by using an Acoustic Doppler Velocimeter (ADV) and a Particle Image Velocimeter (PIV). The CFD models boundary conditions are based on laboratory measurements. Air-water two-phase flows are considered in the simulations. The closure problem is solved by using a two-equations turbulence model. Water depths, hydraulic jumps lengths and velocity profiles are compared with laboratory measurements.
Sustainability, 2020
Hydrogen sulfide (H2S) generated in sewer networks induces corrosion which today constitutes the ... more Hydrogen sulfide (H2S) generated in sewer networks induces corrosion which today constitutes the main cause of deterioration of concrete pipes. Information regarding the H2S concentration inside sewer networks, as well as its control and reduction, has become one of the most important concerns in sanitation systems management nowadays. Modeling sulfide dynamics is the key to understanding corrosion processes. A dynamic model (called EMU-SANETSUL) was developed to calculate the H2S concentration in both the water and the gas phases of the main sewers of the city of Murcia (Spain). The model was calibrated with data from field measurements taken from both the gas phase and wastewater. Samples were taken in the network from 2016 to 2019. The model achieved an accuracy index and error index in the ranges of 57% and 15%, respectively. Empirical equations of reaction are used, and calibration parameters are detailed. The code uses an explicit discretization technique, named the Discrete V...
Ingeniería del agua, 2019
El flujo en vertido en lámina libre constituye uno de los métodos de disipación de energía más ut... more El flujo en vertido en lámina libre constituye uno de los métodos de disipación de energía más utilizados en el sobrevertido de presas. Este artículo presenta el análisis temporal y frecuencial de registros de presiones medidos en la solera de un cuenco de disipación de un aliviadero de vertido libre. Las mediciones han sido realizadas en un dispositivo experimental de tamaño relativamente grande (altura de caída de hasta 2.84 m y velocidades del chorro incidente entre 5.3 y 7.6 m/s). Se han analizado los comportamientos en el dominio del tiempo y de la frecuencia de los cuatro tipos de chorros de aliviaderos de vertido libre clasificados en estudios previos. El estudio se centra en el punto de estancamiento y en las distribuciones de presiones en su entorno. Finalmente, se ha realizado una comparativa de las frecuencias obtenidas con resultados existentes en la bibliografía para chorros circulares y rectangulares.
Sustainability, 2018
A generalized methodology applicable to any urban sub-catchment to calculate the pollution curve ... more A generalized methodology applicable to any urban sub-catchment to calculate the pollution curve due to combined sewer overflows would help to implement integrated management policies to reduce urban impacts on the environment. An existing methodology to predict the pollutographs associated to rainfall events is tested in five different sub-catchments with very different pluviometry. Ninety-three rainfall events have been considered by measuring the in-sewer turbidity along the runoff episodes. Such data is then evaluated to obtain two prediction indices: the time to peak of pollutograph ITPP, and the maximum turbidity concentration ICMAX. These indices may be used with linear regressions to calculate the characteristics of pollutographs, such as the time to the peak, TPP, the maximum concentration of turbidity, CMAXtb, and the time to descent, TDP. These parameters allow to estimate the pollutographs of a sub-catchment. The comparison between pollutographs measured in the Ensanche ...
Environmental Fluid Mechanics, 2019
In recent decades, the advancement of knowledge on the hydraulics of labyrinth weirs has resulted... more In recent decades, the advancement of knowledge on the hydraulics of labyrinth weirs has resulted mainly from physical modeling. In this study, numerical simulations of free-flow and submerged labyrinth weirs were conducted for a large sidewall angle, using commercially available computational fluid dynamics software, for three different turbulence models. These simulations were compared with experimental data gathered in a fairly largescale facility. In general, very good agreement was found on the discharge capacity, in free-flow and submerged conditions, regardless of the turbulence model tested. A dimensionless approaching free surface profile, which was virtually independent of the relative upstream head, was obtained. Downstream of the weir, under subcritical flow conditions, the numerical flow depths agreed reasonably well with the corresponding experimental data.
Water, 2018
Flow over bottom racks is highly turbulent, three-dimensional and spatially varied. The design of... more Flow over bottom racks is highly turbulent, three-dimensional and spatially varied. The design of bottom intake systems has mainly been studied in the laboratory. The comparison of existing experimental studies shows large deviations in the definition of design parameters such as wetted rack length. Each experimental study is limited to a single bar type or to a low range of void ratios, which makes it difficult to generalize the observed data. A combination of empirical, dimensional and inspectional analysis is presented as a useful tool to reduce the number of variables with influence in the design parameters, such as the wetted rack length or the mean discharge coefficient. This work includes a broad experimental campaign in which wetted rack length and mean discharge coefficient are characterized using five different bottom racks with different void ratios (area between bars divided by total area). T-shaped flat and circular bars are considered as well as five different longitud...
Water, 2018
Obstruction of the racks in bottom intakes due to sediment wedged in the slit of the bars can sig... more Obstruction of the racks in bottom intakes due to sediment wedged in the slit of the bars can significantly reduce diverted flow. Notwithstanding the design recommendations that are found in the literature, the problem of rack occlusion continues to occur in built structures. This work focuses on the clogging effects in the circular bars of a bottom rack system using gravels whose median diameter, d50, is close to the spacing between the bars. An experimental campaign including 24 tests, each repeated time times, with six different longitudinal slopes from 0 to 35% and four different specific incoming flow rates, q1, in the range of 0.115 to 0.198 m3/s/m, is presented. The results show the inefficiency of circular profiles in comparison with T-shaped bars. No important influence of rack slope is found that could help to reduce clogging. This works confirms the importance of the selection of bar profile to reduce maintenance labor. A comparison of results with previous works with gra...
Water, 2017
Storm water overflows have an important impact on the environment in many European countries. Now... more Storm water overflows have an important impact on the environment in many European countries. Nowadays, a better knowledge of combined sewer overflows (CSOs) pollution is required for implementing measures to reduce these emissions. In this work, pollution flows mobilized during rainy events have been monitored and modeled in two urban catchments located in the city of Murcia (southeast Spain). For each analyzed event, rainfall volume, in-sewer turbidity and water flow depth have been continuously measured. Therefore, sets of pollutographs and hydrographs have been obtained for each event analyzed. Characteristic variables have been defined and obtained for each event such as the maximum concentration of turbidity, the total event rainfall, the previous dry weather period, the time to the peak of the hydrograph and to the peak of the pollutograph, among others. Relations between variables have been adjusted through a statistical model. The adjusted parameters are used to generate pollutographs that are compared with those measured in field. The present work provides tools to assist in the knowledge of pollution transported through sewer network during stormy events, suggesting the creation of design pollutographs which may facilitate the evaluation of measures to reduce urban runoff pollution.
Journal of Hydroinformatics, 2017
Knowing the scarcity of water in the southeast of Spain and how the rain occurs, we considered th... more Knowing the scarcity of water in the southeast of Spain and how the rain occurs, we considered the design of intake systems in ephemeral riverbeds in order to try to capture part of the runoff flow. The intake systems generally consist of a rack located in the bottom of a river channel, so that the water collected passes down the rack and leads to the side channel. This behaviour has been studied in the laboratory by several researchers. However, due to the many effects that occur on the bars, it is not possible to analyse the whole problem of characterization with traditional methodologies. For instance, the wetted rack length necessary to collect a required flow presents important differences depending on what each author has considered relevant. Computational fluid dynamics simulations have been done to improve the knowledge of the hydraulic phenomenon observed in different laboratory experiences, for which we have previously calibrated the numerical models using laboratory resul...
Sustainability, 2017
Chemical and biological processes consume dissolved oxygen (DO) in urban wastewater during transp... more Chemical and biological processes consume dissolved oxygen (DO) in urban wastewater during transportation along sewer systems. Anaerobic conditions (DO < 0.2 mg/L) are easily reached, leading to sulfide (S 2−) generation. Release of free sulfide, hydrogen sulfide gas (H 2 S), from the liquid to the gaseous phase, causes odor, corrosion of pipes and supposes a risk for health of people working in sewers. These issues get worse in force mains, due to inability to take oxygen from the gaseous phase of pipe. Air injection is a suggested practice to control H 2 S emission in force mains. That technique aims to keep aerobic conditions in wastewater in order to avoid sulfide generation and favor a decrease of Biochemical Organic Demand (BOD). However, several force mains with air injection are not achieving their goals due to a limited oxygen transfer. Field measurements of dissolved oxygen in urban wastewater are presented in an existing force main with air injection during the summer of 2014 in the southeast of Spain. A laboratory scale model is constructed to quantify two-phase flow conditions in pipe due to air injection for different incoming flows rates of water and air. Particularly, for the case of plug flow, also known as elongated bubble flow. Velocity field measurement of water phase in laboratory allows estimating turbulent diffusivity of oxygen in the water, E m , and inter-phase mass transfer coefficient K L (T). In the laboratory, flow and air depth, bubble length, water velocity field, pressure inside force main and water and airflow rates are determined experimentally. These variables are used to assess DO in water phase of force main by comparison with those obtained from field measurements. This work allows assessing air injection efficiency in wastewater, and, therefore, to predict DO in wastewater in force mains.
Water, 2017
The study analyzes the flow over bottom racks made of longitudinal T-shaped bars. A clear water f... more The study analyzes the flow over bottom racks made of longitudinal T-shaped bars. A clear water flow is considered in a laboratory flume. Free surface profiles, wetted rack lengths, and discharge coefficients are measured, changing parameters such as longitudinal slope, void ratio, and approaching flow. The present work complements existing experimental studies, considering the influence of the approaching flow conditions. The velocity field measured with Particle Image Velocimetry (PIV) technique and the pressure field with Pitot tubes are quantified. Numerical simulations (CFD) are used to complement laboratory data. The energy head along the rack is calculated and compared with the hypothesis of horizontal energy level with minimum energy at the beginning of the rack. A discharge coefficient adjustment that considers the slope, the void ratio, and the position along the rack is proposed and presented with the results of other works. Theoretical proposals to calculate the pressure field along the flow are compared with measurements in the laboratory. The relation between the static pressure head in the space of bars and the discharge coefficient is used as an alternative method to define the discharge.
Water, 2016
Rainfall runoff collection in ephemeral streams is an objective in semi-arid zones. Rack intake s... more Rainfall runoff collection in ephemeral streams is an objective in semi-arid zones. Rack intake systems are proposed to collect these flash floods with intensive sediment transport. The design parameters address the problem of clogging the spacing between bars. Experiments for two different void ratio racks are shown. Flows, longitudinal slopes in the rack, and water with three gravel-sized sediments were tested. Results such as effective void ratio due to the gravel deposition over the rack, the evolution of the flow rejected during each test, and the quantification of materials collected and deposited, are presented. The optimal longitudinal rack slope seems to be close to 30%. The effective void ratio is related to several hydraulic parameters calculated at the beginning of the rack. Some adjustments were proposed to predict the effective void ratio.
Water, 2016
Paute-Cardenillo (owned by Celec Ep-Hidropaute) is a dam with maximum height 135 m located in the... more Paute-Cardenillo (owned by Celec Ep-Hidropaute) is a dam with maximum height 135 m located in the Paute River in Ecuador. Its hydroelectric production will be integrated at the National Electric System of Ecuador with an installed capacity of 600 MW which will produce 3300 GWh per year. To evaluate the stability and safety of the structure, it is necessary to ascertain the shape and dimensions of the scour generated downstream from the dam. We studied the scour, due to the operation of the free surface spillway (700 m 3 /s) and half-height outlets (1760 m 3 /s), with three complementary procedures: empirical formulae obtained in models and prototypes, semi-empirical methodology based on pressure fluctuations-erodibility index and computational fluid dynamics simulations. The free surface weir could generate a scour around 21 m, while the intermediate outlet could reach the intact rock, located 34 m below the initial river bed. A pre-excavated basin is proposed and the velocities and pressures are analyzed. The results demonstrated the suitability of combining different methodologies to achieve an adequate resolution of this complex phenomenon.
This work is focused on the study of bottom rack intake systems located in ephemeral and torrenti... more This work is focused on the study of bottom rack intake systems located in ephemeral and torrential streams. Clear water, and water with gravel sediments 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 been also modeled with computational fluid dynamics, and compared with the measured obtained at Universidad Politécnica de Cartagena. 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.
Rectangular jet or nappe flow constitutes one of the energy dissipation methods in arch dams. The... more Rectangular jet or nappe flow constitutes one of the energy dissipation methods in arch dams. The high turbulence and aeration phenomena that appear in fall jets and dissipation basins make difficult to carry out their characterization only based in classical methodologies: reduced models and empirical formulae. The Hydraulics Laboratory of the Universidad Politécnica de Cartagena (Spain) has an infrastructure designed specifically for the study of turbulent jets and energy dissipation in plunge pools. The device allows us to study air-water two-phase phenomena (aeration, spray, spread and impact). The mobile mechanism lets us to vary the discharge heights between 1.70 and 4.00 m and flows between 10 and 150 l/s. To improve the knowledge of the phenomenon of turbulent jets, we are measuring aeration rates by means of fiber optical equipment, velocities in different sections of the stilling basin with Doppler instrumentations and pressures on the bottom of the plunge pool with piezoresistive transducers. Computational Fluid Dynamics programs (CFD) are based on numerical solution of the Reynolds Averaged Navier-Stokes (RANS) equations, together with turbulence models of different degrees of complexity. The programs simulates the interaction between different fluids, such as the air-water two-phase flows, and constitute a new and powerful tool that could let contrast and complement the lab measurement. There are many studies modeling spillways with CFD methodology using different eddy viscosity turbulence models with accurate results. However, the study of overflow nappe impingement jets has not been sufficiently studied. Scale effects are important effects that need to be taking account. In this study, numerical simulations has been carry out using different scales ratio of the lab device according to Froude similarity (1:1; 1:10; 1:20 and 1:40). This paper compares the Parametric Methodology proposed by Castillo (2006, 2007) for the evaluation of hydrodynamic action in plunge pools, revised by Castillo and Carrillo (2011, 2012), with more and new laboratory measurements and the simulation results obtained with CFD program.
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Papers by José Germán Rodríguez Carrillo