In this paper the description of the internal flow in a Francis turbine is addressed from a numer... more In this paper the description of the internal flow in a Francis turbine is addressed from a numerical point of view. The simulation methodology depends on the objectives. On the one hand, steady simulations are able to provide the hill chart of the turbine and energetic losses in its components. On the other hand, unsteady simulations are required to investigate the fluctuating pressure dynamics and the rotor-stator interaction. Both strategies are applied in this paper to a working Francis turbine in Colombia. The employed CFD package is ANSYS-CFX v. 11. The obtained results are in good agreement with the in site experiments, especially for the characteristic curve.----- Keywords: CFD, turbulence, Francis turbine, steady and unsteady simulations
108 El Hombre y la Máquina No. 30 • Enero- Junio de 2008
particles in turbulent flows Resumen Este artículo estudia las características principales del tr... more particles in turbulent flows Resumen Este artículo estudia las características principales del transporte de partículas no esfé-ricas isométricas, con diferentes grados de esfericidad, en un flujo turbulento. La fracción de carga másica de partículas es suficientemente pequeña para tener un flujo muy diluido y poder despreciar la colisiones entre las partículas. Como pri-mera aproximación, tan solo se considera la fuerza de resistencia aerodinámica actuando sobre las partículas, despreciándose tanto la fuerza de sustentación como la rotación de las partículas. El coeficiente de resistencia se cal-cula a través de las correlaciones de Haider y Levenspiel (1989), y Ganser (1993). Las simulaciones numéricas se comparan con los Photographs of the non-spherical particles employed in this work. Duroplastic I (up left), duroplastic II (up right), quartz (bottom left) and polycarbonate (bottom right).
The objective of this article is to review the methodologies used in the last 15 years to estimat... more The objective of this article is to review the methodologies used in the last 15 years to estimate the power loss in wind turbines due to their exposure to adverse meteorological conditions. Among the methods, the use of computational fluid dynamics (CFD) for the three-dimensional numerical simulation of wind turbines is highlighted, as well as the use of two-dimensional CFD simulation in conjunction with the blade element momentum theory (BEM). In addition, a brief review of other methodologies such as image analysis, deep learning, and forecasting models is also presented. This review constitutes a baseline for new investigations of the icing effects on wind turbines’ power outputs. Furthermore, it contributes to a continuous improvement in power-loss prediction and the better response of icing protection systems.
In order to estimate the hydraulic behavior of a drinking water storage tank, Computational Fluid... more In order to estimate the hydraulic behavior of a drinking water storage tank, Computational Fluid Dynamic (CFD) simulation program was used to numerically evaluate blend speed and time profiles. Speed profiles showed a maximum value when leaving at 0.76 m.s-1 and 0.2 m.s-1 speeds near walls, creating recirculation areas near the inlet stream. Injection of tracer and the variation coefficient for 17 monitoring points in the tank resulted in a blend time of 19.06 hours and it was found that the blend near walls is less efficient than in the inlet stream trajectory. Necessary volume to enter the tank in order to achieve a good blend was inversely proportional to the water mass stored.
This paper presents a numerical study of the effects of the inclination angle of the turbine rota... more This paper presents a numerical study of the effects of the inclination angle of the turbine rotation axis with respect to the main flow direction on the performance of a prototype hydrokinetic turbine of the Garman type. In particular, the torque and force coefficients are evaluated as a function of the turbine angular velocity and axis operation angle regarding the mainstream direction. To accomplish this purpose, transient simulations are performed using a commercial solver (ANSYS-Fluent v. 19). Turbulent features of the flow are modelled by the shear stress transport (SST) transitional turbulence model, and results are compared with those obtained with its basic version (i.e., nontransitional), hereafter called standard. The behaviour of the power and force coefficients for the various considered tip speed ratios are presented. Pressure and skin friction coefficients on the blades are analysed at each computed turbine angular speed by means of contour plots and two-dimensional p...
Se llevó a cabo una evaluación a escala real de las condiciones de mezcla y su influencia sobre l... more Se llevó a cabo una evaluación a escala real de las condiciones de mezcla y su influencia sobre la calidad del agua en un tanque de compensación del sistema de distribución de agua potable de la ciudad de Cali (Colombia). El estudio hidrodinámico con aplicación continua de trazador y mediciones de temperatura y de cloro residual libre para identificar el régimen de mezcla en su interior, tiempos de residencia, estratificación térmica y la variación del cloro en el agua almacenada, evidenciaron el comportamiento propio de un tanque de compensación. Se encontró además que la recirculación y el intercambio insuficiente de agua, los bajos de flujo de momento asociados a caudales pequeños y la estratificación térmica puntual pueden causar elevados tiempos de residencia en el tanque, altas edades del agua, mezcla insuficiente y pérdida importante del cloro residual libre. La metodología aplicada en este estudio es apropiada para la evaluación y optimización de tanques de compensación en s...
This paper presents a numerical study of the effects of the inclination angle of the turbine rota... more This paper presents a numerical study of the effects of the inclination angle of the turbine rotation axis with respect to the main flow direction on the performance of a prototype hydrokinetic turbine of the Garman type. In particular, the torque and force coefficients are evaluated as a function of the turbine angular velocity and axis operation angle regarding the mainstream direction. To accomplish this purpose, transient simulations are performed using a commercial solver (ANSYS-Fluent v. 19). Turbulent features of the flow are modelled by the shear stress transport (SST) transitional turbulence model, and results are compared with those obtained with its basic version (i.e., nontransitional), hereafter called standard. The behaviour of the power and force coefficients for the various considered tip speed ratios are presented. Pressure and skin friction coefficients on the blades are analysed at each computed turbine angular speed by means of contour plots and two-dimensional p...
Hydrodynamic phenomena take place within water treatment plants associated with physical, operati... more Hydrodynamic phenomena take place within water treatment plants associated with physical, operational and environmental factors which can affect the water quality. This study evaluated a hydraulic clarifier's hydrodynamic pattern using sludge recircula-tion through continuous tracer test leading to determining hydraulic behaviour indicators and simplified flow models. The clarifier had dual flow with a predominantly complete mixture during the hours in which higher temperatures were reported for affluent water compared to those reported inside the reactor, causing the formation of density currents promoting mixing in the reactor and increased turbidity in the effluent. The hydraulic indicators and the Wolf-Resnick model had higher sensitivity to the influence of temperature on reactor hydrodynamics.
This paper presents aeromechanical evaluation of a blade (length, 50 m) of horizontal axis wind t... more This paper presents aeromechanical evaluation of a blade (length, 50 m) of horizontal axis wind turbines (HAWT). Aerodynamic module combines three-dimensional non-linear lifting surface theory approach and a two-dimensional panel method for steady axisymmetric flow. It provides effective incident velocity and angle of attack at each blade section and 3D pressure distribution on blade as an input data for finite element analysis (FEA) package. FEA provides deformations, strains and stress distributions along blade and material induced fatigue. Degradation linear accumulation model was used in fatigue study under one million cycles of loading. Calculated accumulated damage was found below critical value.
This study presents further developments in Euler/Lagrange approach to calculate confined particl... more This study presents further developments in Euler/Lagrange approach to calculate confined particle-laden flows in pneumatic conveying lines. Special emphasis is placed on influence of particle-wall collisions and wall roughness as well as interparticle collisions with possible agglomeration on developing two-phase flow structure and resulting process parameters. Models and numerical method were validated based on pressure drop measured along a 6 m horizontal channel, and agreement was found to be excellent for different particles sizes, mass loading and wall roughness. In a horizontal pipe flow, due to wall roughnessinduced focussing of particle trajectories towards the core of pipe, a secondary flow in pipe cross-section develops. Additional pressure drop due to particles in pipe flow was higher than that in channel due to different wall collision behaviour.
In this paper the description of the internal flow in a Francis turbine is addressed from a numer... more In this paper the description of the internal flow in a Francis turbine is addressed from a numerical point of view. The simulation methodology depends on the objectives. On the one hand, steady simulations are able to provide the hill chart of the turbine and energetic losses in its components. On the other hand, unsteady simulations are required to investigate the fluctuating pressure dynamics and the rotor-stator interaction. Both strategies are applied in this paper to a working Francis turbine in Colombia. The employed CFD package is ANSYS-CFX v. 11. The obtained results are in good agreement with the in site experiments, especially for the characteristic curve.
In this paper the transient three- dimensional ∞ow developing in a cylindrical lab- oratory bubbl... more In this paper the transient three- dimensional ∞ow developing in a cylindrical lab- oratory bubble column is addressed from a nu- merical point of view. The simulation scheme combines a Large Eddy Simulation (LES) for describing the liquid phase and a Lagragian approach for the gas phase (discrete bubbles) phase. The bubble equation of motion con- siders all the relevant forces, i.e., buoyancy, ∞uid stresses, drag, added mass and transverse lift. From the calculations, the transverse lift in combination with the drag is identifled as the main mechanism allowing the bubbles to spread over the column cross-section. The liq- uid and gas velocity proflles obtained are com- pared with experimental data and ki" results. As a matter of fact, the dynamic structure of the liquid ∞ow induced by the rising bubbles is well reproduced and also good quantitative re- sults for all measured variables of both phases, gas and liquid, are obtained.
This paper deals with non-uniform turbulent particle-laden jet flows. These flows are frequently ... more This paper deals with non-uniform turbulent particle-laden jet flows. These flows are frequently found in industry and are characterized by a large value of the particle fluctuating-velocity anisotropy, much larger than the one corresponding to the carrier phase. As the classical Eulerian and Lagrangian approaches to the description of the dispersed phase fail in the estimation of such anisotropy, two extended Eulerian models for the particle phase are introduced in this work; one of them is algebraic (the Algebraic Particle Stress (APS) model) and the other one is differential (the Particle Reynolds Stress (PRS) model). The performance of these two Eulerian models and a classical Lagrangian approach is evaluated against some experimental measurements available in the literature. The PRS model provides results in good agreement with the experiments for all available variables, including the particle fluctuating-velocity anisotropy. The differential equations that describe the disper...
The present study analyses the pressure drop in a particle-laden six meters long horizontal chann... more The present study analyses the pressure drop in a particle-laden six meters long horizontal channel, with rectangular cross-section from both, experimental and numerical perspectives. Experiments and calculations are carried out for different spherical particles and mass loadings. Additionally, stainless
The study of vertical axis turbines has gained great interest in recent years for its great poten... more The study of vertical axis turbines has gained great interest in recent years for its great potential. Computational fluid dynamics (CFD) is an alternative analysis tool that is being used for the understanding of the problem. This paper presents and discusses the results of the computational parametric study of the airfoil of the blades in a turbine Darrieus type H. We assessed the influence of two parameters: thickness and curvature on the hydrodynamic performance estimated by CFD. We designed a factorial experiment 32, in which each factor had 3 levels, thickness (6, 12 and 15) and symmetry / asymmetry (00XX, 24XX and 44XX). The 9 final simulations were performed in the commercial software Fluent, while the mesh was parameterized in the commercial software Gridgen. The hydrodynamic performance of the turbine was evaluated by analyzing three nondimensional coefficients: Coefficient of moment (Cm), tangential force coefficient (Ct) and radial force coefficient (Cn). Numerical resul...
Para estimar el comportamiento hidraulico de un tanque de almacenamiento de agua potable se uso u... more Para estimar el comportamiento hidraulico de un tanque de almacenamiento de agua potable se uso un programa para la simulacion de dinamica computacionalde fluidos, evaluando numericamente los perfiles de velocidad y el tiempo de mezcla.Los perfiles de velocidad mostraron un valor maximo a la salida de 0,76 m.s-1y velocidades de 0,2 m.s-1 cerca de las paredes, propiciando zonas de recirculacioncerca del chorro de entrada. La inyeccion del trazador y el coeficiente de variacionpara 17 puntos de monitoreo en el tanque resultaron en un tiempo de mezcla de19,06 horas y se verifico que cerca de las paredes la mezcla es menos eficiente queen la trayectoria del chorro de entrada. El volumen necesario que debe entrar altanque para que haya buena mezcla resulto inversamente proporcional a la masa deagua almacenada.
This paper explores the influence of inter-particle collisions in the particle phase variables in... more This paper explores the influence of inter-particle collisions in the particle phase variables in the configuration of a free turbulent round jet laden with solids, i.e., considering the so-called four-way coupling. As a result, and due to the absence of walls confining the flow, the effects of particle-particle interactions start to be relevant for larger mass loading ratios as compared with confined flows, such as those occurring in pipes or channels. However, the particle phase fields are modified similarly to what happens in the previous confined flows: the profile of mean axial velocity flattens and the turbulence tends to be more isotropic when inter-particle collisions are taken into account.
Nuevo modelo euleriano-euleriano para flujos bifásicos turbulentos dispersos
LA TESIS SE PROPONE Y ANALIZA UN NUEVO MODELO PARA FLUJOS BIFASICOS TURBULENTOS CON FASE DISPERSA... more LA TESIS SE PROPONE Y ANALIZA UN NUEVO MODELO PARA FLUJOS BIFASICOS TURBULENTOS CON FASE DISPERSA CONSTRUIDO SOBRE UN MODELO PRECURSOR REFORMADO. EL CITADO MODELO SURGE TANTO DE LA MEJORA Y REFORMULACION DE LOS CIERRES DE LAS CORRELACIONES, EN ESPECIAL EN LO CONCERNIENTE A LA FASE DISPERSA, COMO EN MENOR MEDIDA, DE LA REVISION DEL FORMALISMO DE PROMEDIACION ESTADISTICA CONDICIONADA QUE, APLICADO A LA DEDUCCION DE LAS ECUACIONES DIFERENCIALES QUE DESCRIBEN LA FASE CONTINUA EN UN SISTEMA BIFASICO DISPERSO. TAL MODELO, UNA VEZ ESTUDIADOS LOS MECANISMOS BASICOS SUBYACENTES, SE HA CALIBRADO Y CONTRASTADO SUFICIENTEMENTE MEDIANTE LA CONFIGURACION DE CHORRO LIBRE TURBULENTO. ELLO HA PERMITIDO CONFIRMAR SU ADECUACION PARA EL TRATAMIENTO DE LOS FLUJOS ABORDADOS, SIENDO ESPECIALMENTE ACERTADO EN LA PREDICCION DEL COMPORTAMIENTO DE SISTEMAS BIFASICOS CON PARTICULAS PARTICULAS DE GRAN INERCIA. EN LO QUE RESPECTA A LAS ECUACIONES QUE CONFORMAN EL MODELO, SE HA CONSIDERADO LA RELEVANCIA DE UN NUE...
In this work the turbulent particle dispersion in an underlying flow is addressed by using numeri... more In this work the turbulent particle dispersion in an underlying flow is addressed by using numerical simulation. The proposed approach uses an existing computational code in the Fluid Mechanics Research Group of the UAO, which has been extended in order to improve the numerical predictions of the particle phase turbulent properties in two-phase flow laden with solids.
Avaliação das condições de mistura e sua influência sobre o cloro residual em tanques de compensação de um sistema de distribuição de água de abastecimento
In this paper the description of the internal flow in a Francis turbine is addressed from a numer... more In this paper the description of the internal flow in a Francis turbine is addressed from a numerical point of view. The simulation methodology depends on the objectives. On the one hand, steady simulations are able to provide the hill chart of the turbine and energetic losses in its components. On the other hand, unsteady simulations are required to investigate the fluctuating pressure dynamics and the rotor-stator interaction. Both strategies are applied in this paper to a working Francis turbine in Colombia. The employed CFD package is ANSYS-CFX v. 11. The obtained results are in good agreement with the in site experiments, especially for the characteristic curve.----- Keywords: CFD, turbulence, Francis turbine, steady and unsteady simulations
108 El Hombre y la Máquina No. 30 • Enero- Junio de 2008
particles in turbulent flows Resumen Este artículo estudia las características principales del tr... more particles in turbulent flows Resumen Este artículo estudia las características principales del transporte de partículas no esfé-ricas isométricas, con diferentes grados de esfericidad, en un flujo turbulento. La fracción de carga másica de partículas es suficientemente pequeña para tener un flujo muy diluido y poder despreciar la colisiones entre las partículas. Como pri-mera aproximación, tan solo se considera la fuerza de resistencia aerodinámica actuando sobre las partículas, despreciándose tanto la fuerza de sustentación como la rotación de las partículas. El coeficiente de resistencia se cal-cula a través de las correlaciones de Haider y Levenspiel (1989), y Ganser (1993). Las simulaciones numéricas se comparan con los Photographs of the non-spherical particles employed in this work. Duroplastic I (up left), duroplastic II (up right), quartz (bottom left) and polycarbonate (bottom right).
The objective of this article is to review the methodologies used in the last 15 years to estimat... more The objective of this article is to review the methodologies used in the last 15 years to estimate the power loss in wind turbines due to their exposure to adverse meteorological conditions. Among the methods, the use of computational fluid dynamics (CFD) for the three-dimensional numerical simulation of wind turbines is highlighted, as well as the use of two-dimensional CFD simulation in conjunction with the blade element momentum theory (BEM). In addition, a brief review of other methodologies such as image analysis, deep learning, and forecasting models is also presented. This review constitutes a baseline for new investigations of the icing effects on wind turbines’ power outputs. Furthermore, it contributes to a continuous improvement in power-loss prediction and the better response of icing protection systems.
In order to estimate the hydraulic behavior of a drinking water storage tank, Computational Fluid... more In order to estimate the hydraulic behavior of a drinking water storage tank, Computational Fluid Dynamic (CFD) simulation program was used to numerically evaluate blend speed and time profiles. Speed profiles showed a maximum value when leaving at 0.76 m.s-1 and 0.2 m.s-1 speeds near walls, creating recirculation areas near the inlet stream. Injection of tracer and the variation coefficient for 17 monitoring points in the tank resulted in a blend time of 19.06 hours and it was found that the blend near walls is less efficient than in the inlet stream trajectory. Necessary volume to enter the tank in order to achieve a good blend was inversely proportional to the water mass stored.
This paper presents a numerical study of the effects of the inclination angle of the turbine rota... more This paper presents a numerical study of the effects of the inclination angle of the turbine rotation axis with respect to the main flow direction on the performance of a prototype hydrokinetic turbine of the Garman type. In particular, the torque and force coefficients are evaluated as a function of the turbine angular velocity and axis operation angle regarding the mainstream direction. To accomplish this purpose, transient simulations are performed using a commercial solver (ANSYS-Fluent v. 19). Turbulent features of the flow are modelled by the shear stress transport (SST) transitional turbulence model, and results are compared with those obtained with its basic version (i.e., nontransitional), hereafter called standard. The behaviour of the power and force coefficients for the various considered tip speed ratios are presented. Pressure and skin friction coefficients on the blades are analysed at each computed turbine angular speed by means of contour plots and two-dimensional p...
Se llevó a cabo una evaluación a escala real de las condiciones de mezcla y su influencia sobre l... more Se llevó a cabo una evaluación a escala real de las condiciones de mezcla y su influencia sobre la calidad del agua en un tanque de compensación del sistema de distribución de agua potable de la ciudad de Cali (Colombia). El estudio hidrodinámico con aplicación continua de trazador y mediciones de temperatura y de cloro residual libre para identificar el régimen de mezcla en su interior, tiempos de residencia, estratificación térmica y la variación del cloro en el agua almacenada, evidenciaron el comportamiento propio de un tanque de compensación. Se encontró además que la recirculación y el intercambio insuficiente de agua, los bajos de flujo de momento asociados a caudales pequeños y la estratificación térmica puntual pueden causar elevados tiempos de residencia en el tanque, altas edades del agua, mezcla insuficiente y pérdida importante del cloro residual libre. La metodología aplicada en este estudio es apropiada para la evaluación y optimización de tanques de compensación en s...
This paper presents a numerical study of the effects of the inclination angle of the turbine rota... more This paper presents a numerical study of the effects of the inclination angle of the turbine rotation axis with respect to the main flow direction on the performance of a prototype hydrokinetic turbine of the Garman type. In particular, the torque and force coefficients are evaluated as a function of the turbine angular velocity and axis operation angle regarding the mainstream direction. To accomplish this purpose, transient simulations are performed using a commercial solver (ANSYS-Fluent v. 19). Turbulent features of the flow are modelled by the shear stress transport (SST) transitional turbulence model, and results are compared with those obtained with its basic version (i.e., nontransitional), hereafter called standard. The behaviour of the power and force coefficients for the various considered tip speed ratios are presented. Pressure and skin friction coefficients on the blades are analysed at each computed turbine angular speed by means of contour plots and two-dimensional p...
Hydrodynamic phenomena take place within water treatment plants associated with physical, operati... more Hydrodynamic phenomena take place within water treatment plants associated with physical, operational and environmental factors which can affect the water quality. This study evaluated a hydraulic clarifier's hydrodynamic pattern using sludge recircula-tion through continuous tracer test leading to determining hydraulic behaviour indicators and simplified flow models. The clarifier had dual flow with a predominantly complete mixture during the hours in which higher temperatures were reported for affluent water compared to those reported inside the reactor, causing the formation of density currents promoting mixing in the reactor and increased turbidity in the effluent. The hydraulic indicators and the Wolf-Resnick model had higher sensitivity to the influence of temperature on reactor hydrodynamics.
This paper presents aeromechanical evaluation of a blade (length, 50 m) of horizontal axis wind t... more This paper presents aeromechanical evaluation of a blade (length, 50 m) of horizontal axis wind turbines (HAWT). Aerodynamic module combines three-dimensional non-linear lifting surface theory approach and a two-dimensional panel method for steady axisymmetric flow. It provides effective incident velocity and angle of attack at each blade section and 3D pressure distribution on blade as an input data for finite element analysis (FEA) package. FEA provides deformations, strains and stress distributions along blade and material induced fatigue. Degradation linear accumulation model was used in fatigue study under one million cycles of loading. Calculated accumulated damage was found below critical value.
This study presents further developments in Euler/Lagrange approach to calculate confined particl... more This study presents further developments in Euler/Lagrange approach to calculate confined particle-laden flows in pneumatic conveying lines. Special emphasis is placed on influence of particle-wall collisions and wall roughness as well as interparticle collisions with possible agglomeration on developing two-phase flow structure and resulting process parameters. Models and numerical method were validated based on pressure drop measured along a 6 m horizontal channel, and agreement was found to be excellent for different particles sizes, mass loading and wall roughness. In a horizontal pipe flow, due to wall roughnessinduced focussing of particle trajectories towards the core of pipe, a secondary flow in pipe cross-section develops. Additional pressure drop due to particles in pipe flow was higher than that in channel due to different wall collision behaviour.
In this paper the description of the internal flow in a Francis turbine is addressed from a numer... more In this paper the description of the internal flow in a Francis turbine is addressed from a numerical point of view. The simulation methodology depends on the objectives. On the one hand, steady simulations are able to provide the hill chart of the turbine and energetic losses in its components. On the other hand, unsteady simulations are required to investigate the fluctuating pressure dynamics and the rotor-stator interaction. Both strategies are applied in this paper to a working Francis turbine in Colombia. The employed CFD package is ANSYS-CFX v. 11. The obtained results are in good agreement with the in site experiments, especially for the characteristic curve.
In this paper the transient three- dimensional ∞ow developing in a cylindrical lab- oratory bubbl... more In this paper the transient three- dimensional ∞ow developing in a cylindrical lab- oratory bubble column is addressed from a nu- merical point of view. The simulation scheme combines a Large Eddy Simulation (LES) for describing the liquid phase and a Lagragian approach for the gas phase (discrete bubbles) phase. The bubble equation of motion con- siders all the relevant forces, i.e., buoyancy, ∞uid stresses, drag, added mass and transverse lift. From the calculations, the transverse lift in combination with the drag is identifled as the main mechanism allowing the bubbles to spread over the column cross-section. The liq- uid and gas velocity proflles obtained are com- pared with experimental data and ki" results. As a matter of fact, the dynamic structure of the liquid ∞ow induced by the rising bubbles is well reproduced and also good quantitative re- sults for all measured variables of both phases, gas and liquid, are obtained.
This paper deals with non-uniform turbulent particle-laden jet flows. These flows are frequently ... more This paper deals with non-uniform turbulent particle-laden jet flows. These flows are frequently found in industry and are characterized by a large value of the particle fluctuating-velocity anisotropy, much larger than the one corresponding to the carrier phase. As the classical Eulerian and Lagrangian approaches to the description of the dispersed phase fail in the estimation of such anisotropy, two extended Eulerian models for the particle phase are introduced in this work; one of them is algebraic (the Algebraic Particle Stress (APS) model) and the other one is differential (the Particle Reynolds Stress (PRS) model). The performance of these two Eulerian models and a classical Lagrangian approach is evaluated against some experimental measurements available in the literature. The PRS model provides results in good agreement with the experiments for all available variables, including the particle fluctuating-velocity anisotropy. The differential equations that describe the disper...
The present study analyses the pressure drop in a particle-laden six meters long horizontal chann... more The present study analyses the pressure drop in a particle-laden six meters long horizontal channel, with rectangular cross-section from both, experimental and numerical perspectives. Experiments and calculations are carried out for different spherical particles and mass loadings. Additionally, stainless
The study of vertical axis turbines has gained great interest in recent years for its great poten... more The study of vertical axis turbines has gained great interest in recent years for its great potential. Computational fluid dynamics (CFD) is an alternative analysis tool that is being used for the understanding of the problem. This paper presents and discusses the results of the computational parametric study of the airfoil of the blades in a turbine Darrieus type H. We assessed the influence of two parameters: thickness and curvature on the hydrodynamic performance estimated by CFD. We designed a factorial experiment 32, in which each factor had 3 levels, thickness (6, 12 and 15) and symmetry / asymmetry (00XX, 24XX and 44XX). The 9 final simulations were performed in the commercial software Fluent, while the mesh was parameterized in the commercial software Gridgen. The hydrodynamic performance of the turbine was evaluated by analyzing three nondimensional coefficients: Coefficient of moment (Cm), tangential force coefficient (Ct) and radial force coefficient (Cn). Numerical resul...
Para estimar el comportamiento hidraulico de un tanque de almacenamiento de agua potable se uso u... more Para estimar el comportamiento hidraulico de un tanque de almacenamiento de agua potable se uso un programa para la simulacion de dinamica computacionalde fluidos, evaluando numericamente los perfiles de velocidad y el tiempo de mezcla.Los perfiles de velocidad mostraron un valor maximo a la salida de 0,76 m.s-1y velocidades de 0,2 m.s-1 cerca de las paredes, propiciando zonas de recirculacioncerca del chorro de entrada. La inyeccion del trazador y el coeficiente de variacionpara 17 puntos de monitoreo en el tanque resultaron en un tiempo de mezcla de19,06 horas y se verifico que cerca de las paredes la mezcla es menos eficiente queen la trayectoria del chorro de entrada. El volumen necesario que debe entrar altanque para que haya buena mezcla resulto inversamente proporcional a la masa deagua almacenada.
This paper explores the influence of inter-particle collisions in the particle phase variables in... more This paper explores the influence of inter-particle collisions in the particle phase variables in the configuration of a free turbulent round jet laden with solids, i.e., considering the so-called four-way coupling. As a result, and due to the absence of walls confining the flow, the effects of particle-particle interactions start to be relevant for larger mass loading ratios as compared with confined flows, such as those occurring in pipes or channels. However, the particle phase fields are modified similarly to what happens in the previous confined flows: the profile of mean axial velocity flattens and the turbulence tends to be more isotropic when inter-particle collisions are taken into account.
Nuevo modelo euleriano-euleriano para flujos bifásicos turbulentos dispersos
LA TESIS SE PROPONE Y ANALIZA UN NUEVO MODELO PARA FLUJOS BIFASICOS TURBULENTOS CON FASE DISPERSA... more LA TESIS SE PROPONE Y ANALIZA UN NUEVO MODELO PARA FLUJOS BIFASICOS TURBULENTOS CON FASE DISPERSA CONSTRUIDO SOBRE UN MODELO PRECURSOR REFORMADO. EL CITADO MODELO SURGE TANTO DE LA MEJORA Y REFORMULACION DE LOS CIERRES DE LAS CORRELACIONES, EN ESPECIAL EN LO CONCERNIENTE A LA FASE DISPERSA, COMO EN MENOR MEDIDA, DE LA REVISION DEL FORMALISMO DE PROMEDIACION ESTADISTICA CONDICIONADA QUE, APLICADO A LA DEDUCCION DE LAS ECUACIONES DIFERENCIALES QUE DESCRIBEN LA FASE CONTINUA EN UN SISTEMA BIFASICO DISPERSO. TAL MODELO, UNA VEZ ESTUDIADOS LOS MECANISMOS BASICOS SUBYACENTES, SE HA CALIBRADO Y CONTRASTADO SUFICIENTEMENTE MEDIANTE LA CONFIGURACION DE CHORRO LIBRE TURBULENTO. ELLO HA PERMITIDO CONFIRMAR SU ADECUACION PARA EL TRATAMIENTO DE LOS FLUJOS ABORDADOS, SIENDO ESPECIALMENTE ACERTADO EN LA PREDICCION DEL COMPORTAMIENTO DE SISTEMAS BIFASICOS CON PARTICULAS PARTICULAS DE GRAN INERCIA. EN LO QUE RESPECTA A LAS ECUACIONES QUE CONFORMAN EL MODELO, SE HA CONSIDERADO LA RELEVANCIA DE UN NUE...
In this work the turbulent particle dispersion in an underlying flow is addressed by using numeri... more In this work the turbulent particle dispersion in an underlying flow is addressed by using numerical simulation. The proposed approach uses an existing computational code in the Fluid Mechanics Research Group of the UAO, which has been extended in order to improve the numerical predictions of the particle phase turbulent properties in two-phase flow laden with solids.
Avaliação das condições de mistura e sua influência sobre o cloro residual em tanques de compensação de um sistema de distribuição de água de abastecimento
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