Papers by Leopoldo Millan
Mecánica Computacional, 2003
Mecánica Computacional, 2000
En este trabajo se presentan los estudios realizados para evaluar el comportamiento del fluido a ... more En este trabajo se presentan los estudios realizados para evaluar el comportamiento del fluido a traves de los diferentes componentes de una turbina hidniulica del tipo Francis, y la eficiencia de la misma. Estos estudios fueron realizados durante la etapa de licitacion, tomando como base un modelo homologo al presentado en dicho documento para la Central Hidroelectrica de Boyabat, en Turqufa. En este estudio se analizan todos los componentes de la turbina: camara espiraI. predistribuidor, distribuidor, rodete y tuba de aspiracion.
Journal of Theoretical Biology, 1983
In this paper we study a DNA model, which is built by considering all probable sequences, where t... more In this paper we study a DNA model, which is built by considering all probable sequences, where the possibilities of having the base pairs (A-T) or (C-G) in the jth place of the strand helix are considered. This is assumed in order to derive the partition function. From here the denaturation curve is obtained. Finally, some considerations about the correlation coefficients are presented.
Mathematical Modelling, 1987
In this paper we study a tropocollagen model in order to consider the temperature effect. Both si... more In this paper we study a tropocollagen model in order to consider the temperature effect. Both situations with triple helix structure having one and two hydrogen bonds by each set of three amino acid are presented. Ising models are used for evaluating the statistical properties. Finally comparison with the experimental data is considered. The theoretical results agree very well with the experimental points.
This paper deals with the studies made for evaluate the eficiency and flow behaviour through the ... more This paper deals with the studies made for evaluate the eficiency and flow behaviour through the different components of a Francis turbine. These studies were made during the bidding stage, based on a model homologous to that presented for the bid of the Boyabat Powerplant, in Turkey. All the components of the turbine were analized in this work: spiral case, stay vanes, wicket gates, runner and draft tube. This paper shows only one step on IMPSA's design process which is then completed with the measurements and the hill chart drawing on the test rigs.
La Central Hidroelectrica de YANTAN esta situada en la provincia de Guangxi sobre el rio Hongshui... more La Central Hidroelectrica de YANTAN esta situada en la provincia de Guangxi sobre el rio Hongshui, en el sur de China. La Central cuenta con 4 turbinas Francis con una potencia nominal de 305 MW cada una a un salto neto de 59.5 m. El diametro del rodete es de 8 m. En ciertos regimenes de carga las turbinas tienen fuertes fluctuaciones de presion y vibraciones que se trasmiten a la central. En los rodetes se producen fisuras que tienen que ser reparadas periodicamente. Debido a estos problemas IMPSA es contratada para un Servicio de Consultaria Tecnica. La geometria del rodete existente es relevada por personal de la empresa. Como parte del estudio, los problemas son evaluados por simulacion numerica del flujo. Basandose en las caracteristicas del aprovechamiento se disenaran nuevos rodetes que se estudiaran de la misma forma que el rodete actual a traves de simulacion numerica. En este trabajo se presentan las simulaciones realizados para evaluar el comportamiento del fluido a trave...
In this work are presented the studies perfOrmed to evaluate the behavior of the cooling airflow ... more In this work are presented the studies perfOrmed to evaluate the behavior of the cooling airflow in the radial stator duets of one generator-motor. Due to the rotor influence in the speed tangential component it can be produced the Stall phenomena, what may generate the air circulation blocking at the entrance of the stator core radial ducts impairing the machine ventilation. These studies were made during the engineering studies aiming to discard the possibility of the Stall and to look for the optimum geometrical relationships to decrease the pressure drop in the stator entrance ducts. In this particular case, the generator has a very large tangential component. This brought the necessity of the numerical simulation of this phenomenon, to let us to make a prediction of the ventilation behavior in the studied zone. In this work it was analyzed the central part of the generator components both together stator and rotor.
Journal of Theoretical Biology, 1983
In this paper we study a DNA model, which is built by considering all probable sequences, where t... more In this paper we study a DNA model, which is built by considering all probable sequences, where the possibilities of having the base pairs (A-T) or (C-G) in the jth place of the strand helix are considered. This is assumed in order to derive the partition function. From here the denaturation curve is obtained. Finally, some considerations about the correlation coefficients are presented.
amcaonline.org.ar
Esta presentación trata sobre el diseño, test y evaluación de las fuerzas hidráulicas en un rodet... more Esta presentación trata sobre el diseño, test y evaluación de las fuerzas hidráulicas en un rodete Kaplan de reemplazo para la central hidroeléctrica de Dahua, en Guangxi, R.P. China. La central existente consta de cuatro turbinas Kaplan de 8.5m de diámetro, de seis álabes cada una y de 103 MW de potencia. Los rodetes nuevos tienen el mismo diámetro, cinco álabes y la potencia incrementada a 117 MW. Durante la etapa de licitación las garantías presentadas fueron basadas en un modelo similar ya ensayado. Las principales diferencias se encontraban en la cámara semi-espiral, la tapa de la turbina y el tubo difusor. Se realizaron simulaciones del comportamiento del flujo para evaluar las pérdidas de eficiencia debidas a estas diferencias. El modelo análogo disponible y el rodete de reemplazo fueron estudiados usando un programa de volúmenes finitos 3D. Este resuelve las ecuaciones de Navier-Stokes promediadas con un modelo turbulento de dos ecuaciones (k-ε) y una función de pared. El resto de los componentes del pasaje de agua existente: cámara semi-espiral, álabes del predistribuidor y distribuidor y el tubo difusor también fueron analizados para una evaluación total de las pérdidas. Extensos ensayos de modelo se llevaron a cabo para confirmar los datos garantizados de: eficiencia, comportamiento en cavitación, fluctuaciones de presión y velocidad de embalamiento. También se realizaron otras mediciones especiales tales como empuje axial y torque en los álabes del rodete y distribuidor. En los ensayos de campo (Abril de 1999), se superó la potencia garantizada, y se verificó la estabilidad de la turbina.
IEEE Journal of Quantum Electronics, 1980
The system of two nonlinear differential equations for a three-level laser is solved exactly. It ... more The system of two nonlinear differential equations for a three-level laser is solved exactly. It relates the number of photons q(t) in the laser cavity and the population inversion n(t). The functions n(t) and q(t) are expanded in a power series and two recurrence relations are obtained. These are solved and the solutions are in excellent agreement with experimental results.
Mathematical Modelling, 1987
In this paper we study a tropocollagen model in order to consider the temperature effect. Both si... more In this paper we study a tropocollagen model in order to consider the temperature effect. Both situation with triple helix structure having one and two hydrogen bonds by each set of three amino acid are presented. Ising models are used for evaluating the statistical properties. Finally comparison with the experimental data is considered. The theoretical results agree very well with the experimental points.
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Papers by Leopoldo Millan