Generalized Definition of Flame Stretch for 3D Instationary Premixed Flames

摘要

The flame stretch concept is formulated for the general case of 3D instationaryflames with finite flame front thickness. It is shown that additional contributions to the stretch rate appear apart from the terms which are usually used in flame studies. These extra terms are associated with variations in the mass density along the flame iso-contours and with variations in flame front thickness in time and space. It is finally shown that the following definition for the stretch rate is generally applicable: K = 1/m x dm/dt, denoting the fractional change of mass in an infinitesimally small flame volume.