A computational technique for the evaluation of dynamic effects of exothermic reactions

✍ Scribed by L.M. Cohen; J.M. Short; A.K. Oppenheim

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 872 KB
• Volume: 24
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(75)90165-0

✦ Synopsis

The paper presents a computational technique for the analysis of nonsteady flow fields generated by exothermic reactions in a compressible medium. This is obtained by numerical integration of the set of rate equations of chemical kinetics combined with the set of conservation equations of nonsteady gasdynamics expressed in a Lagrangian form. Under the hypothesis that the power pulse of exothermic energy is so short that the effects of diffusion, viscosity, and conductivity are, during its effective life span, negligible, the place where it is generated can be restricted to a discrete Lagrangian cell, and, consequently, the chemical kinetic set expressed in terms of ordinary differential equations. The computational model devised in this manner is referred to as the exothermic center. Conceptually, it is a simple flow field, which consists of a kernel, confined within a single Lagrangian cell around the center where the exothermic reaction takes place, and of inert surroundings through which the pressure wave generated by the expanding kernel propagates, the two separated from each other by an impermeable interface.

The computations yield the characteristic features of the power pulse of work done by the kernel on the surroundings. On the basis of this information, complex flow fields, where exothermic processes occur, can be analyzed as a nonsteady (diabatic) flow subject to energy (heat) supply that is furnished at a predetermined rate and given as a function of local thermodynamic state parameters, as demonstrated in the companion paper presented at the 15th Symposium (International) on Combustion.