Large eddy simulation of explosion deflagrating flames using a dynamic wrinkling formulation

Abstract

Reliable predictions of flames propagating in a semi-confined environment are vital for safety reasons, once they are representative of accidental explosion configurations. Large eddy simulations of deflagrating flames are carried out using a dynamic flame wrinkling factor model. This model, validated from a posteriori analysis, is able to capture both laminar and turbulent flame regimes. At early stages of the flame development, a laminar flame propagates in a flow essentially at rest and the model parameter is close to zero, corresponding to a unity-wrinkling factor. Transition to turbulence occurs when the flame interacts with the flow motions generated by thermal expansion and obstacles. The model parameter and wrinkling factor take higher values at these stages. Three configurations investigated experimentally by Masri et al. 2012, corresponding to different scenarios of flame acceleration are simulated. The first case (OOBS) is characterized by a long laminar phase. In the second one (BBBS) the flame is the most turbulent and the highest overpressure is observed in the vessel. For the last case (BOOS), the flame front is relaminarized after crossing the first row of obstacles. In all configurations, large eddy simulations (LES) predict the flow dynamics and maximum overpressure with good accuracy.