Browsing by Autor "Alix Teresa Moncada Moreno"

Now showing 1 - 7 of 7

Disipador radial imperfecto
(2001) Alix Teresa Moncada Moreno; Julián Aguirre; María Luisa Olivero
In the past, the hydraulic circular jump formed by the defection of a jet on a perpendicular plane has been studied. Functional relationships for the sequent depth as a function of the Froude Number of the deflected jet and of the height of the retention wall have obtained. The dissipation of energy has also been found. In this paper, a theoretical and experimental study on an imperfect circular jump is studied. This jump is formed for small radii and high heights of the retention walls. For these conditions, the upstream and downstream flows are not uniform anymore. A theoretical general equation, that allows to predict the dimensionless submergence depth as a function of five different parameters, was developed. An additional relationship to calculate the dissipation of energy, in the circular imperfect hydraulic jump, was obtained. Results of laboratory experiments, to verify the applicability of the theoretical analysis, are given. Coefficients that satisfy the fundamental equations are numerical obtained.
Efecto de la granulometría en el transporte de sedimentos
(2002) Julián Aguirre; Alix Teresa Moncada Moreno; María Luisa Olivero; Mauricio Andrés Ruiz Ochoa
In this work the sediment transport in function of the densimetric Froude number is calibrated. The study is based on a 46 experiments set realized with gravel of average diameter D50 = 0,0071 m. The obtained function is applied to the ideal condition of uniform diameter finding relatively moderate error compared with the transport measurements. Then the transported sediment is divided in fractions of characteristic diameters Di and diverse methodologies to calculate the sediment transport are applied. As a result, all of them compared with the measured values produce great error estimations, but if the Karim exposition and hiding correction (1998) is applied to the calibrated transport ratio the calculating error found, with the unique diameter D50, diminishes appreciably. It is recommended thus, to divide the sediment carried in fractions and to determine the transport of each fraction. This way the average error on transport estimation is reduced from 184% for diameter D50 to 102% for the diameters corresponding to the different fractions.
Efecto de un aro sobre la socavación en pilas circulares
(2007) Alix Teresa Moncada Moreno; Julián Aguirre; Juan Bolívar; Edgar Flores
In this paper an experimental study in order to analyze the effect of using a collar around a circular pier as device for controlling the depth of scour was made. Experiments were conducted using a circular pier of 7.3 cm diameter and two collars of different size. In the first stage a collar of 14.6 cm diameter was placed around the pier and, subsequently, a collar of 21.9 cm was used. The collar was placed at different positions with regard to the bed level. In each experiment the profile of the scoured bed, upstream and downstream of the pier was measured. This allowed to determine the maximum scour depth and to study the influence of the size and the position of the collar on the size and form of the scour hole. From the experimental information it is showed that the profiles of the scoured holes are similar in nature independently of the size and the position of the collar. It is found that when the collar is placed at the bed level the minimum depth of scour is produced. It is also obtained that the scour depth is reduced when the diameter of the collar is increased. The results are contrasted with the available little information in previous studies.
Efecto del número de Froude densimétrico en el transporte de sedimentos
(2001) Julián Aguirre; María Luisa Olivero; Alix Teresa Moncada Moreno
In this paper, critical conditions for the initiation of particle motion are considered for ratios depth to bed particle less than 10 (flow on very rough boundaries). Here, a densimetric Froude number of the particles is analysed as an alternative criterion to predict hydraulic conditions for the initiation of motion. Critical densimetric Froude numbers of the particles were determined after calibration with available laboratory data. Some of the most employed formulations to estimate bed material transport in high slope macro-rough flows are described. Most of the theories consider the excess of boundary shear stress, above the critical shear stress, as the dominating parameter that defines sediment transport. Two procedures, that were specifically developed to predict sediment transport in high slope streams, are presented. One of them considers the excess of a dimensionless discharge, above the critical discharge, the second one incorporates the influence of the densimetric Froude number of the particles, in excess of its critical value. A new transport function, that shows a better behavior than the previously analyzed formulations, is proposed in this paper for high slope macro-rough streams.
Optimización del uso de modelos de transporte de sedimentos en canales y ríos mediante análisis comparativo
(Universidad Autónoma del Estado de México, 2007) Daniel Machado; Julián Aguirre; Alix Teresa Moncada Moreno; María Luisa Olivero
"Existen muchos fenómenos mecánicos complejos, uno de ellos es el transporte de sedimento por corrientes de a en él influyen múltiples variables. Entre éstas se distinguen propiedades del cauce, del sedimento y del flujo. Ex gran diversidad de modelos de transporte, al menos 50, por tanto, seleccionar el más adecuado al momento resolver problemas prácticos puede resultar difícil. Buscando optimizar el uso de algunos de ellos se evaluaron modelos de transporte de sedimento del fondo, utilizando un banco de datos de más de 4000 flujos de 34 canale laboratorio y 11 ríos. Se empleó un nuevo indicador de bondad, el índice de error o de exactitud, IE, para comp los modelos. Para el banco de datos depurado, los modelos con mejor comportamiento fueron los de Engelun Hansen (1967) y Aguirre-Pe et al. (2000), con valores promedio IE = 2,79 y 6,17, respectivamente. determinaron rangos de aplicabilidad de los modelos en función de: diámetro medio de sedimentos, pendiente cauce, caudal por unidad de ancho, radio hidráulico y velocidad media de flujo. La influencia de estas cinco varia fue considerada mediante el parámetro adimensional número de Froude densimétrico de las partículas modifi para considerar la pendiente, FS *. Al determinar los rangos de aplicabilidad de los modelos en base a éste se ob que los modelos de Engelund y Hansen (1967) y Karim (1998) presentaron los rangos más amplios. En base a rangos de cada modelo para FSƒx * se desarrolló un método, incluyendo una versión software, para la selecció los modelos más apropiados para estimar el transporte del fondo con fines prácticos. El método desarrollado mo eficiencia del 69% al verificarse con una segunda muestra de 10 canales y ríos. Se podría mejorar el método, po que sería conveniente continuar investigaciones en el área."
Socavación producida por chorros verticales circulares y rectangulares sumergidos
(2002) Alix Teresa Moncada Moreno; Julián Aguirre
In this paper, an experimental research on the local scour phenomenon on sand beds, produced by the impingement of submerged rectangular and circular vertical water jets, is presented. Experiments were carried out in a tank of circular cross section of 0.75 m diameter and height of 0.84 m, with a suitable constant-head arrangement. For the case of circular vertical jets, the mean diameter of the sand particles used as bed material was d50 = 3.1 mm. The circular jet nozzle diameters were 6.5, 12.9 and 16 mm. The discharge supplied to the model varied between 1.67x10-4 and 1.974x10-3 m3/s. In total, 60 experiments were performed. An additional study of rectangular vertical jets was performed. Experiments were carried out varying the rectangular cross section of the nozzle. These had an aspect relation of 2, 4 and 6. Two different sizes of sand were used as bed material. The first granular material was fine sand with d50 = 0.055 cm and the second coarse sand with d50 = 0.14 cm. The discharge varied between 3.8x10-4 and 1.30x10-3 m3/s. For rectangular vertical jets, 90 experiments were performed. From the experimental investigation, empirical relationships that allow to predict the characteristic lengths of the final steady state scour hole are developed.
Soluciones del flujo bifásico granular
(2000) Julián Aguirre; Alix Teresa Moncada Moreno; María Luisa Olivero
Granular two-phase flows may be generated by the sudden displacement of a retention gate. Different criteria may be used to classify two-phase flows: hyperconcentrated flow, mud flow and debris flows. Limits that characterize different flow regimes are given. Numerical solutions using McCormack scheme for the continuity and conservation of momentum equations are presented. Characteristics of the deposition of granular solid material, obtained by a decrease of the channel slope or by sudden increase in its width, are determined. Numerical solutions are compared with a data obtained at the laboratory. It is found that numerical simulations offer a good approach to laboratory data, which represented two different flow conditions: saturated sand flow and flow of a plastic grains for different concentrations.