Numerical and experimental study of atrium enclosure fires in a full scale fire test facility. Póster

For the present work, a 3-D numerical model has been implemented to simulate the thermal and fluid fields induced by an enclosure fire in an atrium and for smoke exhaust system assessment. This study is focused on the ‘Fire Atrium’, a new full-scale fire test facility of the Technological Metal Centre in Murcia, Spain. It is an aluminium prismatic squared base building of 19.5 m x 19.5 m x 20 m with several vents arranged in its walls and four exhaust fans at the roof

On the feasibility of a flexible foil with passive heave to extract energy from low wind speeds

We explore numerically and theoretically the capability of flexible foils elastically mounted to translational springs and dampers at the leading edge to extract energy from low-speed winds through its passive heave motion. Given the spring and foil stiffnesses, for each damper constant the theory (which is valid for high Reynolds numbers and small foil deflection amplitudes, i.e., in absence of separation) provides analytically a minimum wind velocity for flutter instability, above which energy can be harvested, that depends on the thickness-to-chord-length ratio of the foil. Simple analytical expressions for the flutter frequency are also provided. Minimum wind speeds and corresponding flutter frequencies are characterized for a carbon fiber foil as the spring stiffness and damper constant are varied, finding that energy can be extracted from wind speeds lower than in conventional wind turbines. These theoretical predictions are assessed from full numerical simulations at Reynolds numbers corresponding to these wind velocities and for chord lengths of the order of the meter (i.e. about 106 ) using appropriate turbulence models, which allow to compute the power extracted from the wind that the flutter stability analysis cannot provid

Force and torque reactions on a pitching flexible aerofoil

Experimental measurements in a wind tunnel of the unsteady force and moment that a fluid exerts on flexible flapping aerofoils are not trivial because the forces and moments caused by the aerofoil's inertia and others structural tensions at the pivot axis have to be obtained separately and subtracted from the direct measurements with a force/torque sensor. Here we derive from the nonlinear beam equation general relations for the force and torque reactions at the leading edge of a pitching aerofoil in terms of the fluid force and moment on the aerofoil and its kinematics, involving geometric and structural parameters of the flexible aerofoil. These relations are validated by comparing high-resolution numerical simulations of the flow–structure interaction of a two-dimensional flexible aerofoil pitching about its leading edge with direct force and torque measurements in a wind tunnel.This research has been supported by the Junta de Andalucía, Spain (UMA18-FEDER-JA-047 and P18-FR-1532). Funding for open access charge: Universidad de Málaga

Low and medium power full-scale atrium fire tests and numerical validation of FDS

The inclusion of atria within modern large buildings is relative recent. These structures are important architectonical features since the 60’s. Atria are a source of discussion within the fire science community. They introduce complex designs and non conventional architectonical elements that can lead to fire environments diverging from those in current codes. Because of this, the current trend in fire safety in atria is towards performance based design. At this point, it is still necessary to improve and validate the existing numerical models. For this aim, some tests were carried out at the Murcia Fire Facility. These consist of 19 full-scale fire tests that provide with new experimental data of atrium fires. The fire size, the smoke extraction rate and make-up openings size and location were varied. At the present paper, a set of results from some of these experiments in a 20 m cubic facility are reported and discussed. Additionally, comparisons with the predicted results from Fire Dynamics Simulator (FDS) v.4 are also presented. FDS has turned out to be capable to predict the transient fire-induced conditions inside the facility accurately, above all at the upper parts. The predicted smoke layer descent has been also compared with the experimental one with good agreement.The authors want to acknowledge the Centro Tecnológico del Metal of Murcia for the use of their test rig, the Professor J. L. Torero, T. Steinhaus, C.Abecassis-Empis, P. Reszka, W. Jahn, from the University of Edinburgh, for their technical suggestions and supervision. Simulations have been carried out at the computational facilities of the Technological Research Services of the Technical University of Cartagena (SAIT) and the University of Jaen. This work has been supported by Ministerio de Educación y Ciencia of Spain (Projects CT/G30572473, and FIT-020700-2004-25 and grant TRA2006-15015) and by the Junta de Andalucía of Spain (Project number P07-TEP-02693)

Método y sistema de evaluación de transformaciones morfológicas de una cavidad nasal

Número de publicación: 2 732 713 Número de solicitud: 201830500Método y sistema de evaluación de transformaciones morfológicas de una cavidad nasal que comprende, para cada transformación morfológica (ax) bajo análisis, simular (550) un flujo (F) en un modelo tridimensional modificado (Mx 3D) por dicha transformación morfológica (ax) y analizar al menos un primer parámetro (ϕ) y un segundo parámetro (R) calculados (560) a partir de dicho flujo (F) y dicho modelo tridimensional modificado (Mx 3D). El primer parámetro (ϕ) es una medida de asimetría morfológica y fluido-dinámica, mientras que el segundo parámetro (R) es una medida de resistencia bilateral de la combinación del pasaje nasal izquierdo y del pasaje nasal derecho. El primer parámetro (ϕ) y el segundo parámetro (R) se comparan (570) con unas condiciones de validación (570), obteniendo así una evaluación (ev) de cada transformación morfológica (ax) bajo análisis.Universidad Politécnica de Cartagen

On the Fluid Dynamics of the Make-Up Inlet Air and the Prediction of Anomalous Fire Dynamics in a Large-Scale Facility

The present paper is focused on the fluid dynamics of the make-up air at the vents in case of an atrium fire, its influence on the fire-induced conditions and the necessity of properly model it to obtain an accurate numerical prediction. For this aim, experimental data from two full-scale atrium fire tests conducted in a 20 m cubic facility, with venting conditions involving mechanical smoke exhaust and make-up air velocities larger than 1 m/s, and with different fire powers, are presented. Subsequent numerical simulations of these tests have been performed with the code Fire Dynamics Simulator v5.5.3. Two different approaches have been followed to simulate the make-up air inlet fluid dynamics, involving one domain which only considers the inside of the building and another which includes part of the outside. In the former simulations, anomalous phenomena around the fire appear, while the inclusion of the exterior domain provides with a completely different fluid dynamics inside the facility which agrees better with the experimental data. A detailed analysis of the fluid mechanics at the air inlet vents is conducted to explain these discrepancies. Finally, further simulations are performed varying the make-up area to assess the appearance of the aforementioned phenomenon.This research was supported by the Spanish MCyT and Junta de Andalucia under Projects # DPI2008-06624-C03-02 and # P07-TEP02693, respectively. CGM wants to acknowledge the research stay grants IAC-2010-3 and A-13-2010 from the Junta de Andalucia and the University of Jaén, respectivel

Estudio numérico experimental de un incendio controlado en una nave industrial. Póster

Se ha desarrollado un modelo numérico para la simulación de los campos fluido y térmico que genera un incendio en el interior de una nave industrial. La nave es la Nave del Fuego del Centro Tecnológico del Metal (Alcantarilla, Murcia). Esta nave tiene unas dimensiones de 19,5 x 19,5 x 17,5 m con un techo piramidal de altura 2,5 m. Consta de cuatro extractores de ventilación en la parte superior del techo y una serie de rejillas de ventilación en la parte inferior de las paredes. El fuego se sitúa en el centro del suelo de la nave. Para este trabajo se ha realizado una parte experimental y una numérica. Se han realizado ensayos experimentales con diferentes potencias de fuego y topologías de ensayo. Se han realizado simulaciones numéricas estacionarias y transitorias. En este trabajo se realiza la comparación de los resultados obtenidos numéricamente con los medidos durante un ensayo experimental realizado, con características similares

A validated CFD methodology to obtain the total pressure loss coefficients in Internal compressible flow at junctions

A global methodology has been developed and validated to obtain the total pressure loss coefficient in internal compressible flow at T-type junctions. This methodology is based on the calculation of the thermo-fluid properties extrapolated to the branch axes intersection, once the straight pipe friction losses numerically calculated have been subtracted from the total energy losses. For this purpose, a steady adiabatic compressible one-dimensional flow with friction mathematical model has been applied to the results obtained by numerical simulation using the commercial finite volume code FLUENT. A 90 degree T-type junction has been studied and the predicted loss coefficient has been related to the extrapolated Mach number in the common branch and to the mass flow rate ratio between branches at different flow configurations, in both combining and dividing flows. The numerical results have been compared with experimental results and published data in open literature. In general, a good agreement is obtained. The correlations obtained will be applied as boundary condition in one-dimensional global simulation models of fluid systems in which these components are present.This research has been supported by the Seneca project PB/19/FS/97 Comunidad Autónoma Región de Murcia (experimental facilities) and MCYT project DPI2003-02719 (software). The numerical simulations have been made in the computer facilities at the SAIT (Universidad Politécnica de Cartagena)

Numerical model and validation experiments of Atrium enclosure fire in a new fire test facility

The use of CFD as a tool for building, warehouses oro facories design requirements fulfilling about fire safety is becoming more common and reliable. Performance-based fire safety assurance procedures make use of the CFD fire modelling to evolution of fire, but they need always to be validated. This is especially difficult for big structures, with great clear volumes, where effects of natural and forced ventilation can be very scale dependent. A good opportunity to check the prediction capability of CFD codes to establish temperatures and velocities fields is the new full-scale fire test facility of the Technological Metal Centre in Murcia, Spain. It is an aluminium prismatic squared base building of 19.5m x 19.5m x 20m, with several vents arranged in its walls and four exhaust fans at the roof. Series of experimental tests have been carried out using several heptane normalized pool-fires placed at the centre of the atrium.The data obtained from these experiments have been later used in a validation study of two CFD simulations implemented for temperature wall, ambient temperature prediction and exhaust fan assessment. The results show good agreement between experimental and numerical predictions and ventilation system is not enough to extract the hot combustion products. There is an excessive and dangerous accumulation of hot gases at the upper part of the atrium and the exhaust capacity of the roof fan must be increased. The CFD models can give the answer to that question.The authors want to acknowledge the Technological Metal Centre of Murcia for the use of their test rigs, the SAIT (Technological Research Service of the Technical University of Cartagena) and the University of Jaen for the use of their entire computing resources and their technical support. This work has been supported by Ministerio de Educación y Ciencia of Spain (grants DPI2005-08654-C04-01 and TRA2006-15015)