chapter  11
10 Pages

VORTICITY AND ENTRAINMENT IN A JET SUBJECTED TO OFF-SOURCE VOLUMETRIC HEATING

Entrainment and mixing are problems of major concern when one attempts to

understand, control, or model combustion ows in air-breathing propulsion sys-

tems, as well as in such geophysical problems as the evolution of clouds. A

variety of experimental studies carried out in recent years have illuminated the

connections between the coherent structures found in turbulent shear ows and

entrainment, chemical reaction, and combustion [1{3]. It is important to realize

that in experiments on reacting ows, the heat released is a result of chemi-

cal reactions, and that the rate of such reactions is determined by the amount

of mixing (in the sense of molecule-to-molecule interaction) that takes place.

The mixing itself depends on | and in turn aects, through the chemical reac-

tion | the structure of turbulence in the ow. Turbulence, mixing, and reaction

this cyclical connection between mixing, combustion, and heat release can be

broken, and one may focus on the specic eect on turbulence of substantial

amounts of heat release. With this objective in view, a series of simulations have

been performed here using a pseudospectral method to compute the evolution

of a jet-like ow with volumetric heat injection.