Modelling of Hydrogen Jet Fires Using CFD

The computational fluid dynamics (CFD) software FLACS has primarily been developed to model dispersion and explosion phenomena; however models for the simulation of jet fires are under development. The aim is to be able to predict industrial fires efficiently and with good precision.  Newly developed models include e.g. flame models for non-premixed flames, discrete transfer radiation model as well as soot models. Since the time scales for fire simulations are longer than for explosions, the computational speed is important. The recent development of non-compressible and parallel solvers in FLACS may therefore be important to ensure efficiency. Hydrogen flames may be invisible, will generate no soot and tend to radiate less than hydrocarbon fuels. Due to high pressure storage the flame lengths can be significant. Simpler jet flame relations can not predict the jet flame interaction with objects and barriers, and thus the heat loads on impacted objects. The development of efficient and precise CFD-tools for hydrogen fires is therefore important. In this paper the new models for the simulation of fire are described. These models are currently under development and this manuscript describes the current status of the work. Jet fire experiments performed by Health and Safety Laboratories (HSL), both free jets and impinging jets, will also be simulated to evaluate the applicability and validity of the new fire models.