Application of computational fluid dynamics techniques to the analysis of building fires

Abstract

This MPhil project includes an investigation of the possibility of utilising Computational Fluid Dynamics (CFD) techniques to predict and recreate the complicated development of fires in buildings of a non-trivial geometry. It also includes comparative studies of different codes in a practical context and an examination of the limitations and adaptability of state of the art general purpose CFD code for fire modelling.
This thesis sets out a detailed literature survey of publications reported about application of CFD software in fire engineering practice with emphasis on compartment fire modelling. The review identifies physical models for turbulence, combustion and
radiation most widely used in CFD fire modelling. The survey also discusses methodology for CFD fire modelling, steps required to apply a CFD software to a practical problem, governing equations for fire related phenomena and properties of
numerical solution.
A substantiation of the necessity to adopt the software to a specific class of problems is given. Verification and validation studies of the CFD software are performed by the examination of test problems of classic CFD (natural convection in a square cavity and backward step flow), combustion (Steckler's experiment), and reproducing results of experiments in the cone calorimeter and in a steel shipping container. Numerical predictions are analysed and the conclusions about adaptability of the software for modelling fire-related processes are made.
CFD techniques are applied both to assess possible CFD methodologies and to predict the impact of a possible fire in the real complex-geometry multi-purpose building (the Printworks, Manchester, UK). For all the fire scenarios considered, two techniques (prescribed volumetric heat source and CFD modelling of buoyant turbulent diflüsion flame) are applied to model the fire source. The role of fire source model is clarified, and new quantitative information is obtained for a possible fire development and smoke movement in the building with potentially high fire hazard. The experience gained through examination of the quality of the results enabled some recommendations for the use of commercial CFD software in fire research.