CaracterizaciĆ³n del flujo medio sobre una turbina eĆ³lica
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Fecha
2018
Autores
Profesor/a GuĆa
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Idioma
es
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Universidad AndrƩs Bello
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Licencia CC
Licencia CC
Resumen
Se implementĆ³ un modelo numĆ©rico del tipo URANS para estudiar las estadĆsticas de la
turbulencia asociadas a un flujo de viento que actĆŗa sobre una turbina eĆ³lica sin rotaciĆ³n
y en rƩgimen permanente. La turbina corresponde al modelo NTK65, de 31 m. de altura
y 16,5 m. de diƔmetro (D). La turbina enfrenta un flujo de viento cuya velocidad promedio
es de 15 m/s en la direcciĆ³n longitudinal, y tiene asociado un nĆŗmero de Reynolds de
aproximadamente 2*107
. La simulaciĆ³n numĆ©rica se llevĆ³ a cabo mediante el software
OpenFOAM. En este trabajo se implementĆ³ el modelo de turbulencia k-3 estĆ”ndar, el cual
a pesar de sus limitaciones para predecir flujos con separaciĆ³n o con fluctuaciones de
velocidad distintas en las tres direcciones, sirve como caso canĆ³nico y de comparaciĆ³n
para modelaciones con cierres de turbulencia mƔs sofisticados. Los perfiles de velocidad
media y dƩficit de velocidad media obtenidos de las simulaciones numƩricas son
cualitativamente similares a los encontrados en la literatura. Se encontrĆ³ que el dĆ©ficit
mƔximo de velocidad a 1D corriente abajo de la turbina es de un 60% y se ubica a una
altura aproximada de 19 m. Haciendo un anĆ”lisis similar, se observĆ³ que a una distancia
de 7D de la turbina, el dƩficit de velocidad es de aproximadamente un 3%, lo cual indica
que el flujo prƔcticamente ha recuperado su perfil de entrada. En otras palabras, el efecto
de la estela sobre el perfil medio de velocidad en dicha ubicaciĆ³n, es bastante pequeƱo.
Respecto a las estadĆsticas de la turbulencia, se encontraron valores mĆ”ximos de
intensidad de turbulencia de un 24%, ubicados entre 0,25D y 1D corriente abajo de la
turbina. Resultados experimentales con turbinas similares, indican que dichos valores
mƔximos se ubican entre 3D y 6D corriente abajo de la turbina. Estas diferencias pueden
ser atribuibles a la advecciĆ³n generada por el movimiento rotatorio de los Ć”labes.
Se espera que el presente trabajo sirva como base para modelar la misma turbina con
modelos de turbulencia mƔs sofisticados, incluyendo tambiƩn el movimiento de los
Ɣlabes.
A URANS type numerical model was implemented to study the turbulence statistics associated with a steady state wind flow that acts on a wind turbine without rotation. The turbine corresponds to the model NTK65, of 31 m. of height and 16,5 m. in diameter (D). The turbine faces a wind flow with an average velocity of 15 m/s in the longitudinal direction, at a Reynolds number of approximately 2*107 . The numerical simulation was carried out using the software OpenFOAM. In this work the standard k-ļ„ turbulence model was implemented, which despite its limitations to predict flows with separation or with different turbulence velocity fluctuations in the three directions, serves as a canonical and a comparison case for turbulence modeling with more sophisticated turbulence closures. The profiles of mean velocity and deficit of mean velocity obtained from the numerical simulations are qualitatively similar to those found in the literature. It was found that the maximum velocity deficit 1D downwind of the turbine was 60%, and it was located at an approximate height of 19 m. Following a similar analysis, it was observed that at a distance of 7D from the turbine, the velocity deficit was approximately 3%, which indicates that the flow has nearly recovered its inlet velocity profile. In other words, the effect of the wake on the average velocity profile at that location is very small. Regarding turbulence statistics, maximum turbulence intensity values of 24%, were found located between 0,25D and 1D downstream of the turbine. Experimental results with similar turbines, indicate that maximum values are located between 3D and 6D downstream of the turbine. These differences may be attributed to the advection generated by the rotary movement of the propeller blades. It is hoped that the present work will serve as a basis for modeling the same turbine with more sophisticated turbulence models, while also including the motion of the blades.
A URANS type numerical model was implemented to study the turbulence statistics associated with a steady state wind flow that acts on a wind turbine without rotation. The turbine corresponds to the model NTK65, of 31 m. of height and 16,5 m. in diameter (D). The turbine faces a wind flow with an average velocity of 15 m/s in the longitudinal direction, at a Reynolds number of approximately 2*107 . The numerical simulation was carried out using the software OpenFOAM. In this work the standard k-ļ„ turbulence model was implemented, which despite its limitations to predict flows with separation or with different turbulence velocity fluctuations in the three directions, serves as a canonical and a comparison case for turbulence modeling with more sophisticated turbulence closures. The profiles of mean velocity and deficit of mean velocity obtained from the numerical simulations are qualitatively similar to those found in the literature. It was found that the maximum velocity deficit 1D downwind of the turbine was 60%, and it was located at an approximate height of 19 m. Following a similar analysis, it was observed that at a distance of 7D from the turbine, the velocity deficit was approximately 3%, which indicates that the flow has nearly recovered its inlet velocity profile. In other words, the effect of the wake on the average velocity profile at that location is very small. Regarding turbulence statistics, maximum turbulence intensity values of 24%, were found located between 0,25D and 1D downstream of the turbine. Experimental results with similar turbines, indicate that maximum values are located between 3D and 6D downstream of the turbine. These differences may be attributed to the advection generated by the rotary movement of the propeller blades. It is hoped that the present work will serve as a basis for modeling the same turbine with more sophisticated turbulence models, while also including the motion of the blades.
Notas
Memoria (Ingeniero Civil)
Palabras clave
Turbinas EĆ³licas, Modelos MatemĆ”ticos, Procesamiento de Datos, Turbulencia, EstadĆsticas