The Laminar Diffusion Flame behind a Blunt Body: a Constant-Pressure Oseen-flow Model

Abstract

Two gas streams, one containing oxidant, the other fuel, are initially separated by a parabolic cylinder whose vertex points in the downstream direction. Behind the body the streams unite to produce a laminar diffusion flame. By assuming that the temperature and species' concentration fields are not affected by pressure changes, a number of general solutions for these fields are found, using a linear theory after the manner of Oseen. Solutions are first found for the Burke-Schumann flame-sheet model of a fast irreversible burning reaction. These prove to be the outer solution in a matched asymptotic expansion treatment of the fast reaction case; the inner solutions provide information on flame structure and serve to link streamwise diffusion flame behaviour with previously-considered stagnation-point flames. Information is obtained about the variations which take place along the flame (roughly, in the streamwise direction) and the influence of a cooled body on the flame is briefly examined.