Towards the Implementation of Rayleigh-Taylor Instability into the Multi-Phenomena Deflagration Model

Data obtained from experiments carried out at the FM Global large scale deflagration chamber have been used to further develop the multi-phenomena deflagration model. This model has been under development at the University of Ulster during the last decade. This expansion of the deflagration model accounts for the inclusion of Rayleigh-Taylor (RT) instability, as an additional time-dependent combustion enhancing mechanism. The previous version of the LES deflagration model without the addition of RT instability underpredicted the experimental results, due to the model not properly capturing the external deflagration observed during the experiment. Following this underprediction, RT instability was identified as playing a significant role in combustion enhancement as the flame front accelerated towards the vent and during combustion outside the enclosure. The implementation of a mechanism to account for RT instability, in the form of an additional time-dependent flame wrinkling factor, led to an intensification of the external deflagration. This resulted in closer agreement between the simulated and experimental pressure transients.