Various flame tracking techniques are often used in hydrodynamic simulations. Their use is indispensable when resolving actual scale of the flame is impossible. We show that parameters defining “artificial flame” propagation found from model systems may yield flame velocities several times distinct from the required ones, due to matter expansion being ignored in the models. Integral effect of m...

To understand the propagation characteristics of methane-air deflagration flames and in an obstacle-filled tube, a high-speed color video camera, photoelectric sensors, and pressure transducers were used to test the deflagration flame propagating parameters. The tests were run in a 1500 mm long plexiglass tube with a 100 × 100 mm square cross-section. The obstacles included four types of repeat...

A new modeling strategy is developed to introduce tabulated chemistry methods in LES of turbulent premixed combustion. The objective is to recover the correct laminar flame propagation speed of the filtered flame front when subgrid scale turbulence vanishes. The filtered flame structure is mapped by 1-D filtered laminar premixed flames. Closure of the filtered progress variable and the energy b...

The aim of this paper is to present some improvements in the metrology of forest fire flames by coupling image processing and radiative heat flux measurement. A new metrological tool using a visual video camera and a specific multiple thermal sensor is proposed. By means of an appropriate segmentation algorithm and the Direct Linear Transformation, the image processing methodology gives the for...

A large eddy simulation (LES) model was developed to simulate the combustion process in a spark-assisted homogeneous charge compression ignition (SACI) engine. First, an ignition and flame propagation model based on a reaction progress variable is presented. The reaction progress variable is defined based on the normalized cumulative heat release. Transport equation for the progress variable is...

The excess enthalpy flames and their dynamics below the flammability limit are studied by considering two flames that propagate in opposite directions in parallel channels. The model enables the coupling between the external heat loss, convection preheating, diffusion transport and finite rate chemistry. Analytical expressions for the flame temperature, separation distance, and extinction limit...

In this study, the effect of flame intrinsic instability on the flame structural characteristics of hydrogen/air mixtures premixed at various equivalence ratios were experimentally investigated from the macroscopic and microscopic perspectives, respectively. The correlation degree and the relative deformation degree were defined to quantitatively study the global flame structural characteristic...

In experiments of hot surface ignition and subsequent flame propagation, a puffing flame instability is observed in mixtures that are stagnant and premixed prior to ignition. By varying the size of the hot surface, power input, and combustion vessel volume, it was determined that the instability is a function of the interaction of the flame, with the fluid flow induced by the combustion product...

Quasi-steady and unsteady propagations of methane and propane–air premixed flames in a mesoscale divergent channel were investigated experimentally and theoretically. The emphasis was the impact of variable cross-section area and the flame-wall coupling on the flame transition between different regimes and the onset of flame instability. Experimentally, for the first time, spinning flames were ...