Estudio numérico de las presiones instantáneas sobre un canal de descarga escalonado
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Fecha
2023
Profesor/a Guía
Facultad/escuela
Idioma
es
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Universidad Andrés Bello
Nombre de Curso
Licencia CC
Licencia CC
Resumen
Este trabajo corresponde a un estudio numérico de presiones instantáneas en puntos de interés de la región no aireada de un vertedero escalonado de gran pendiente, para el que existen mediciones experimentales muy recientes. El objetivo es explotar el registro experimental de presiones instantáneas medidas en las caras vertical y horizontal de los escalones mediante la implementación de un modelo computacional capaz de recoger datos instantáneos de presión de flujo.
El modelo hidráulico elegido es un aliviadero escalonado de 35 escalones y 53 grados de pendiente, con escalones de 6 cm de altura (h) y 4,5 cm de longitud (l). El caudal unitario empleado fue de 0,5 m2/s (q), lo que corresponde a una altura crítica adimensional (yc/h) de 4,9 y un número de Reynolds de aproximadamente 5x105. En estas condiciones, el punto de entrada de aire observado en los experimentos se situó aproximadamente en el escalón 31.
El modelo numérico implementado incluye la misma geometría que el modelo experimental, con un dominio computacional que se extiende hasta el escalón 35, correspondiente al final de la región de flujo no aireado. La comparación entre los valores experimentales y numéricos de presión se llevó a cabo en la parte central de la región no aireada, específicamente en los escalones 11, 12 y 13, a una distancia de 8 mm de los bordes sólidos de los escalones.
Los valores numéricos de las presiones medias fueron obtenidos mediante la aplicación del modelo RANS. Este modelo proporcionó resultados consistentes con las mediciones experimentales. Se implementó un modelo LES/WALE para la estimación de las presiones fluctuantes del modelo. Los resultados revelaron una notable concordancia entre las presiones fluctuantes calculadas y los datos experimentales, logrando una diferencia de 3 puntos para la malla más fina simulada en uno de los escalones, la cual presentaba dimensiones de 2 mm x 3 mm.
Los resultados numéricos obtenidos siguen una distribución muy similar a la obtenida experimentalmente para los valores instantáneos de presión asociados a una probabilidad de excedencia dada. Se analizaron probabilidades de excedencia del 99,9%, 99%, 95%, 50%, 5%, 1% y 0,1% siguiendo la misma metodología que en el estudio experimental.
Este estudio contribuye a una mejor comprensión de las presiones máximas y mínimas en la región no aireada de los vertederos escalonados de gran pendiente y demuestra la validez de nuestra implementación numérica como herramienta de predicción de presiones instantáneas.
This work corresponds to a numerical study of instantaneous pressures at points of interest in the non-aerated region of a steep stepped spillway, for which very recent experimental measurements exist. The objective is to exploit the experimental record of fluctuating pressures measured on both the vertical and horizontal faces of the steps by implementing a computational model capable of collecting instantaneous flow pressure data. The chosen hydraulic model is a stepped spillway with 60 steps and a slope of 53 degrees, with steps measuring 6 cm in height (h) and 4.5 cm in length (l). The employed unit discharge was 0.5 m2/s (q), which corresponds to a dimensionless critical height (yc/h) of 4.9 and a Reynolds number of approximately 5x105. Under these conditions, the observed air entrainment point in the experiments was located approximately at step 31. The implemented numerical model includes the same geometry as the experimental model, with a computational domain extending up to step 35, corresponding to the end of the non-aerated flow region. Comparison among experimental and numerical values of pressure was undertaken in the middle portion of the non-aerated region, specifically at steps 11, 12, and 13, at a distance of eight mm from the solid edges of the steps. The numerical results obtained follow a very similar distribution to that obtained experimentally for instantaneous pressure values associated with a given exceedance probability. Exceedance probabilities of 99.9%, 99%, 95%, 50%, 5%, 1%, and 0.1% were analyzed following the same methodology as the experimental study. The numerical values for mean pressures were obtained using an RAS/k-ε model. This model yielded data consistent with experimental results, particularly during the initial phase of downstream flow development. Subsequently, an LES/WALE model was employed to capture fluctuating pressures from the model. The outcomes demonstrated a noteworthy agreement between the calculated fluctuating pressures and experimental data, achieving an 85% accuracy rate for the finest simulated mesh, measuring 2 mm x 3 mm. This study contributes to a better understanding of maximum and minimum pressures in the non-aerated region of steep stepped spillways and demonstrates the validity of our numerical implementation as a tool for predicting instantaneous pressures.
This work corresponds to a numerical study of instantaneous pressures at points of interest in the non-aerated region of a steep stepped spillway, for which very recent experimental measurements exist. The objective is to exploit the experimental record of fluctuating pressures measured on both the vertical and horizontal faces of the steps by implementing a computational model capable of collecting instantaneous flow pressure data. The chosen hydraulic model is a stepped spillway with 60 steps and a slope of 53 degrees, with steps measuring 6 cm in height (h) and 4.5 cm in length (l). The employed unit discharge was 0.5 m2/s (q), which corresponds to a dimensionless critical height (yc/h) of 4.9 and a Reynolds number of approximately 5x105. Under these conditions, the observed air entrainment point in the experiments was located approximately at step 31. The implemented numerical model includes the same geometry as the experimental model, with a computational domain extending up to step 35, corresponding to the end of the non-aerated flow region. Comparison among experimental and numerical values of pressure was undertaken in the middle portion of the non-aerated region, specifically at steps 11, 12, and 13, at a distance of eight mm from the solid edges of the steps. The numerical results obtained follow a very similar distribution to that obtained experimentally for instantaneous pressure values associated with a given exceedance probability. Exceedance probabilities of 99.9%, 99%, 95%, 50%, 5%, 1%, and 0.1% were analyzed following the same methodology as the experimental study. The numerical values for mean pressures were obtained using an RAS/k-ε model. This model yielded data consistent with experimental results, particularly during the initial phase of downstream flow development. Subsequently, an LES/WALE model was employed to capture fluctuating pressures from the model. The outcomes demonstrated a noteworthy agreement between the calculated fluctuating pressures and experimental data, achieving an 85% accuracy rate for the finest simulated mesh, measuring 2 mm x 3 mm. This study contributes to a better understanding of maximum and minimum pressures in the non-aerated region of steep stepped spillways and demonstrates the validity of our numerical implementation as a tool for predicting instantaneous pressures.
Notas
Tesis de pregrado (Ingeniero Civil)
Palabras clave
Vertederos Escalonados, Modelos Matemáticos, Simulación por Computador, Análisis Numérico.