Many practical combustion systems such as residential gas burners contain dense groupings or clusters of jet flames with sufficiently small spacing between them, which causes flame interaction. The interaction effect, due in part to Oxygen deficiency in the interstitial space between the flames, causes the spreading of flames, which may merge together to form larger group flames. This interactive effect is studied analytically by revisiting the laminar isolated flame theory for 2D jets, for which similarity solutions are readily available in compressible form, and symmetrical interaction zones can be observed. Flame characteristics were studied by obtaining analytical expressions for flame specific parameters such as height and width, lift-off height and blow-off velocity, air entrainment and mixing layer growth. The theory for multiple interacting jets describes an approximate criterion for interburner spacing at which flame interaction and group flame formation are first observed. The analytical framework presented in this paper presented in this paper produced results which were compared with experimental measurements. The experimental apparatus allowed the interburner spacing to be varied from 7.87？mm to 50.8？mm, and measurements of flame height, width, lift-off height and group-flame formation under interactive modes. Images of the evolving flow field were taken and Schlieren images of the multiple 2D jets were also recorded using a digital camera. 1. Introduction In order to study the stability and combustion behavior of interacting jet diffusion flames, laminar single flame stability theory must be developed for a burner and extended to include the effect of multiple burners. In this current work, a stability theory for jets is introduced and the appropriate generalized conservation equations for momentum, species, and energy for 2D compressible systems with boundary conditions are presented. The governing equations are solved to give explicit solutions for axial and radial gas velocities, flame height, maximum flame width and its axial location, amount of air entrainment, lift-off height and blow-off velocity as a function of injection Reynolds number ( ), Schmidt number ( ), and fuel composition. We begin by summarizing relevant literature review corresponding to single-flame combustion. Literature regarding the stability characteristics (lift-off height and blow-off velocity) of single jet diffusion flames is quite extensive. Some of the relevant endeavors are summarized here. Van quickenborne and Van Tiggelen [1] studied the stabilization of
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