Cfd Simulations Of In Situ Airflow Measurements In Road Tunnels

To investigate the performance of current emergency ventilation strategies for an existing road tunnel system in the event of a fire, a research project is being conducted by the National Research Council (NRC) of Canada. The primary objectives of the study are: a) to assess and validate the ability of emergency ventilation strategies to control smoke spread and minimize the impact of smoke on tunnel users; and b) to recommend guidelines for improving the ventilation operation to maximize intervention effectiveness. This will allow future development of an intelligent ventilation system based on a pre-established ventilation scenario activated using automatic fire detection. The current paper presents the initial investigation of comparing the predictions of a CFD model against the onsite flow measurements conducted in the tunnel. A version of this paper is published in Tunnel Management International Journal, v.7 no. 4, Dec. 2004, pp 1-10.

Pressure and flowrate measurements were conducted for an air-cooled salient pole hydro model generator in order to validate a computational fluid dynamics (CFD) simulation approach. The ventilation system of the model generator was driven by adjustable external fans, which allows detailed pressure measurements for a range of operating conditions. The CFD model to be validated consists of full generator geometry which is modelled in high geometrical detail. The steady-state multiple reference frame approach was chosen for the simulations, and the influence of different rotor-stator interfaces and turbulence models was investigated. The comparison of measurement and simulations includes the static pressure along the flow path through the machine, the performance map of the external fans, and an analytical approach to describe the dimensionless machine parameters of the model generator. Good overall agreement was found between measurement and CFD, which justifies the application of the presented simulation approach in the design of ventilation and cooling systems for hydro power generators. Qualitatively the CFD simulations reproduced all measured flow effects. Also quantitatively a good prediction of measured values was identified for a broad range of operating conditions. However, it was found that the simulation accuracy does not only depend on the numerical models in use but also on the specific operating conditions and their affiliated airflow characteristics.

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TRB’s National Cooperative Highway Research Program (NCHRP) 415: Design Fires in Road Tunnels information on the state of the practice of design fires in road tunnels, focusing on tunnel fire dynamics and the means of fire management for design guidance.

Fire and combustion presents a significant engineering challenge to mechanical, civil and dedicated fire engineers, as well as specialists in the process and chemical, safety, buildings and structural fields. We are reminded of the tragic outcomes of ‘untenable’ fire disasters such as at King’s Cross underground station or Switzerland’s St Gotthard tunnel. In these and many other cases, computational fluid dynamics (CFD) is at the forefront of active research into unravelling the probable causes of fires and helping to design structures and systems to ensure that they are less likely in the future. Computational fluid dynamics (CFD) is routinely used as an analysis tool in fire and combustion engineering as it possesses the ability to handle the complex geometries and characteristics of combustion and fire. This book shows engineering students and professionals how to understand and use this powerful tool in the study of combustion processes, and in the engineering of safer or more fire resistant (or conversely, more fire-efficient) structures. No other book is dedicated to computer-based fire dynamics tools and systems. It is supported by a rigorous pedagogy, including worked examples to illustrate the capabilities of different models, an introduction to the essential aspects of fire physics, examination and self-test exercises, fully worked solutions and a suite of accompanying software for use in industry standard modeling systems. Computational Fluid Dynamics (CFD) is widely used in engineering analysis; this is the only book dedicated to CFD modeling analysis in fire and combustion engineering Strong pedagogic features mean this book can be used as a text for graduate level mechanical, civil, structural and fire engineering courses, while its coverage of the latest techniques and industry standard software make it an important reference for researchers and professional engineers in the mechanical and structural sectors, and by fire engineers, safety consultants and regulators Strong author team (CUHK is a recognized centre of excellence in fire eng) deliver an expert package for students and professionals, showing both theory and applications. Accompanied by CFD modeling code and ready to use simulations to run in industry-standard ANSYS-CFX and Fluent software

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