Flammefront

Flammefront is a term used in combustion science to denote the propagating interface between unburned reactants and burned products within a flame. In premixed flames, the flammefront is a thin reaction zone that separates the unburned gas from the hot, chemically transformed products, and its movement through the mixture defines the flame speed.

In laminar flames, the flammefront has a well-defined thickness, typically on the order of millimeters or less, where chemical reactions convert fuel into combustion products. In turbulent flames, the front becomes wrinkled and folded by turbulent eddies, increasing the overall surface area and the effective burning rate. The structure and behavior of the flammefront depend on factors such as fuel–oxidizer mixture, temperature, pressure, and flow conditions.

Flammefronts are central to many combustion models and analyses. They are described using reaction-diffusion frameworks, with approaches such as level-set methods (G-equation) to track the front, or simplified one-dimensional laminar flame models for fundamental insights. Experimental methods to visualize and characterize the flammefront include planar laser-induced fluorescence, chemiluminescence imaging, and Schlieren techniques, which provide measurements of front position, thickness, and burning velocity.

Understanding the flammefront is important for practical applications, including engine efficiency, flame stabilization, and safety considerations related to flame extinction and flashback. The term is widely used across languages, corresponding to Flammenfront in German and similar variants in other languages, and is broadly synonymous with the flame front in combustion science.