Gadur, Sergio N. (2017) Modelado de válvulas de accionamiento pasivo mediante la técnica de sólidos inmersos. / Modeling of passive drive valves through the immersal solid technique. Proyecto Integrador Ingeniería Nuclear, Universidad Nacional de Cuyo, Instituto Balseiro.
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Resumen en español
En la presente tesis se realiza el analisis y evaluacion del tiempo de apertura de valvulas de accionamiento pasivo del reactor experimental RA-6, junto con el modelado numerico de su dinamica ante un evento iniciante. Estas valvulas se encuentran completamente inmersas en el tanque del reactor y permiten pasar al modo de refrigeracion por conveccion natural. Este modo solo puede estar activo si la potencia del reactor es inferior a 200 kW y suele activarse ante transitorios provocados por determinados eventos inciantes en la planta. En particular, se modelara un evento iniciante de perdida del motor de la bomba del circuito de refrigeracion primario, con posterior actuaci´on de las valvulas clapeta. En el modelado numerico de este problema de interacci´on fluido-estructura se utilizo un metodo hıbrido, el cual implementa la tecnica de solidos inmersos y la formulacion ALE para la descripcion del movimento de las mallas tanto del fluido como del solido. Al mismo tiempo se utilizo el sistema GPFEP como herramienta computacional para la resolucion mediante el metodo de elementos finitos de las ecuaciones que gobiernan la fısica del problema. Antes de simular el problema de interes, se realizo la validacion del codigo mediante un problema tıpico de solido inmerso. Tal es el caso de un flujo incompresible que atraviesa un canal rectangular con un obstaculo circular. Se simularon distintos numeros de Reynolds, se calcularon los coeficientes de drag, y los numeros de Strouhal. Se compararon estos resultados con los obtenidos por distintos autores que se mencionan en la Bibliografìa. Posteriormente, se redujo el problema de las válvulas clapeta a un caso bidimensional, conservando cantidades fíısicas representativas del problema a analizar, con el objetivo de disminuir el costo computacional. Se simulo un transitorio en el caudal del sistema de refrigeracion primario, correspondiente al evento iniciante antes mencionado. Se pudo observar la evolucion del campo de presion, la misma muestra que existe una presion critica a partir de la cual se produce la apertura de las valvulas clapeta. El programa permite visualizar la dinamica del movimiento de las valvulas clapeta mientras las mismas se abren. Simultaneamte se observo que la malla del fluido se adapta de manera efectiva al solido, acompañando el movimiento de la valvula, resultado de la adecuada implementacion de la formulacion ALE para mallas moviles.
Resumen en inglés
In the present thesis, the analysis and evaluation of the opening time of passive valves of the experimental reactor RA-6, together with the numerical modeling of its dynamics due to a starting event, is performed. These valves are completely immersed in the tank of the reactor and allow to pass to the natural convection cooling mode. This mode can only be active if the power of the reactor is less than 200 kW and is usually activated after a starting event is induced in the plant. In particular, the starting event of loss of the pump motor of the primary cooling circuit will be modeled, with subsequent actuation of the flap valves. In the numerical model of this fluid-structure interaction problem, a hybrid method was used, which implements the immersed solids technique and the ALE formulation for the description of both mesh movements coming from the fluid and the solid. At the same time, the GPFEP system was used as a computational tool to solve via the finite element method the equations that govern the physics of the problem. Before simulating the problem of interest, a code validation was performed considering a well-known solid immersed problem. Such is the case of an incompressible flow passing across a rectangular channel which contains a circular obstacle. Different Reynolds numbers were simulated, drag coefficients, and Strouhal numbers were calculated. These results were compared with those obtained by different authors mentioned in the Bibliography. Afterward, the problem of valves was reduced to a two-dimensional case, preserving representative physical quantities of the problem to be analyzed, in order to reduce the computational cost. A transitory state was simulated in the flow rate of the primary cooling system, corresponding to the aforementioned starting event. It was possible to observe the evolution of the pressure field, it shows that there is a critical pressure for which the opening of the flap valves takes place. The program allows to visualize the dynamics of the movement of the flap valves as they open. At the same time, it was observed that the mesh of the fluid adapts effectively to the solid, accompanying the movement of the valve, resulting from the proper implementation of the ALE formulation for mobile meshes.
| Tipo de objeto: | Tesis (Proyecto Integrador Ingeniería Nuclear) |
|---|---|
| Palabras Clave: | Loss of coolant; Pérdida de fluidos refrigerante; Safety valves; Válvulas de seguridad; Natural convection; Convección natural; RA-6 reactor; Reactor RA-6 [Arbitrary lagragian eulerian; Enfoque de sólidos inmersos] |
| Referencias: | [1] Constant, E., Li, C., Favier, J., Meldi, M., Meliga, P., Serre, E. Implementation of a discrete inmersed boundary method in openfoam., 2006. 25, 31, 32, 33 [2] Blackburn, H., Henderson, R. A study of two-dimensional flow past an oscillating cylinder. Fluid Mech., pag. 385, 1999. 25, 31, 32 [3] Pinelli, A., Piomelli, U., Favier, J. Inmersed-boudary methodas for general FInitedifference and finite. Journal of Comutational Physics, Navier-Stokes solvers, 299, 2010. 31, 33 [4] Tritton, D. Experiments on the ow past a circular cylinder at low reynolds numbers. Fluid Mech, pag. 6, 1959. 31 [5] Williamson, C. Vortex dynamics in the cylinder wake. Annu. Rev. Fluid. Mech, pag. 28, 1996. 31, 32, 33 [6] Norberg, C. An experimental investigation of the flow around a circular cylinder: influence of aspect ratio. Fluid Mech., pag. 258, 1994. 31, 32 [7] Guimineau, E., Quentey, P. A numerical simulation of vortex seffing from an oscillating circular cylinder. Fluids Struct., pag. 16, 2002. 31 [8] Barkley, D., Henderson, R. Three-dimensional floquet stability analysis of the wake of a circular cylinder. Fluid Mech., pag. 332, 1996. 32 [9] Henderson, R. Details of the drag curve near the onset of vortex shedding. Phys. Fluid, 7, 1995. 32 [10] Vanella, M., Balaras, E. A moving-least-squares reconstruction for embeddedboundary formulations. Comput. Phys., pag. 228, 2009. 33 [11] Lu, X., Dalton, C. Calculation of the timing of vortex formation from an oscillating cylinder. Fluids Struct, 10, 1996. 33 [12] Rajani, B., Kandasamy, A., Sekhar, M. Numerical simulation of laminar flow past a cylinder circular. Applied Mathematical Modelling, 33, 2009. 33 [13] Qu, L., Norberg, C., Davidson, L., Peng, S., Wang, F. Quantitive numerical analysis of flow past a cylinder circular at reynolds number between 50 and 200. Journal of Fluids and Structures, 39, 2013. 33 [14] Mittal, R., Balachandar, S. Generation of stramwise vortical structures in bluff body wakes. Physique Review Letter, 75, 1995. 33 [15] Norberg, C. Pressure force on a circular cylider in cross flow, bluff-body wakes, dynamics and instabilities, 1993. 33 [16] Wieselsberger, C. New data on the law of hydro and aerodynamics resistence, naca tn. 84. 33 [17] Gadur, S. N., Pardo, R. M., Meier, H. Determinacion experimental del caudal de refrigeracion de un elemento combustible estandar para el nucleo del reactor ra-6. pag. 4, 2017. 44 [18] Kundu, P. K., Cohen, I. M., Dowling, D. R. Fluid mechanics. 5, 21-30. 51 |
| Materias: | Física > Mecánica de fluidos |
| Divisiones: | Gcia. de área de Aplicaciones de la tecnología nuclear > Gcia. de Investigación aplicada > Mecánica computacional |
| Código ID: | 621 |
| Depositado Por: | Tamara Cárcamo |
| Depositado En: | 23 Oct 2017 12:03 |
| Última Modificación: | 23 Oct 2017 12:03 |
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