Fire is capable of harming people and damaging structures. During fire safety assessment, it is usually necessary to check that occupants are able to evacuate the environment before being overcome by heat or toxins. Similarly, it is sometimes necessary to determine the structural response to and coupling with the fire. Computational tools for modelling ventilation and fire have advanced rapidly in power and value, along with developments in computers. Computational Fluid Dynamics (CFD) is now capable of running with common-place models of fire and ventilation, as well as more sophisticated and comprehensive models which are more reliable, for example when the fire is underventilated or suppressed by water spray. This paper will describe CFD modelling and its application to the issue of fire suppression by water spray, using the ANSYS-CFX software. Fire safety engineers use two basic approaches for modelling fire: (a) Inert, or (b) Reacting or combusting. Option (a) is easier and cheaper, but less reliable, whereas Option (b) is more complex but is more realistic. A common technique used for modelling fire suppression in the context of (a) has simply involved a reduction of the assumed heat source. This strategy is fundamentally flawed, in that it fails to describe smoke logging. The paper will describe fully-coupled modelling of water spray and the gaseous environment, applied to a machinery space.
展开▼
