Diffusion flames and supersonic combustion 1

Abstract

The paper describes some analytical work connected with
the purely diffusive mode of supersonic combustion.
The basic problems considered have been: the study of
the hydrogen-air diffusion flames, under hoth close to and far from equilibrium conditions, and the study of the aerodynamic field near the injector exit when the ratio of injected to outer total pressures is small.
The internal structure of hydrogen-oxygen diffusion flames close to equilibrium has been studied using the first order approximation of an asymptotic expansion method, in which
the large parameter represents the ratio between a characteristic mechanical time and a chemical time.
Far from equilibrium conditions, the above mentioned
solution fails. However, when a free jet of hydrogen, parallel to the air stream is used for injection purposes, a very simple near frozen approach may be used. The main simplifying features of such an approach being; the use of an overall chemical reaction, the assumption that fuel and oxidizer mix without appreciable depletion and chemical heat release, and the linearization of the mixing problem.
Finally a discussion of some means of improving the
mixing process, near the injector exit, is made, using some
experimental evidence from work on related problems by other
groups.