Numerical solution of the problem of a thermal explosion taking account of free convection

Abstract

The question of the need to consider the influence of free convection on a thermal explosion was f i rs t posed in [i], where it was indicated that the pa ramete r 6 charac ter iz ing the l imits of thermal self-ignit ion should depend on a pa rame te r charac te r iz ing the intensity of natural convection, i .e. , on the Rayleigh (Ra) c r i t e r ion (for gases the Ra c r i te r ion equals the Grashof cr i ter ion). The assumption has been expressed that the influence of convection on a thermal explosion for gases s tar ts to be manifest for values of Ra >_104. The appearance of convective effects at considerably lower values of the Ra c r i te r ion (Ra ~ 600) has been detected in [2] by means of an experimental investigation of the tempera ture distribution in vesse ls with a react ing gas.