Premixed Combustion Flame Instability Characteristics (PREFIC)

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Cellular instability and self-acceleration of premixed flames are commonly observed in fuel combustion, due to the thermal-diffusive and hydrodynamic instability. Cellar instability significantly influences the flame structure and speed, and the resultant self-acceleration has been widely observed in spherical flame studies, with high influences on the turbulent burning velocity of various combustion systems and causing higher fire and explosion hazards. Mapping the regimes of cellular instability and self-acceleration could help improve combustion modelling which is widely used in design of combustion systems and investigation of fire and explosion hazards.The project is divided into two main work packages, in which the research is moving from basic dada acquirement to the cause of instability and in the end of the consequence of self-acceleration. The flame cellular structure will be mathematically characterised and quantified by the microscopic photography and image processing technique rather than traditionally by measuring burning velocity through calculation of flame size or pressure history.A newly defined Cellularity Factor is introduced to represent the flame cellular structure characteristics, and the variation regularity of flame front cells is firstly calculated and analysed by measuring the cellular structure parameters, which are the primary parameters to quantitatively determine the critical point of the fully developed cellular flame and to describe the self-acceleration. Present work will develop a new burning velocity model for flame acceleration.Improved correlations are proposed, incorporating transient and multidimensional effects, as finite rate chemistry, which are crucial for the predictive engineering model developments.