Combustion-source development in a closed vessel in conditions of natural convection

Abstract

The propagation of localized combustion sources in sufficiently large finite volumes has for a long time attracted the interest of researchers, in connection with the need to determine the limits of ignition of fuel mixtures. In the present work, the possibilities of numerical modeling of thermogasdynamic phenomena observed in the development of a source in a closed plane vessel in the field of external forces (gravitational forces) are demonstrated. A closed, plane two-dimensional region of square cross section is considered in the formulation of the problem; this region is filled with fuel mixture, in which a single-stage exothermal reaction of first order with respect to the concentration of the least plentiful reactant may occur. The reaction rate depends on the temperature in accordance with the Arrhenius law. The motion of the reacting gas is described by a system of nonsteady twodimensional equations. The development of the source is considered with ignition both from above and below. Numerical investigation allows a solution to be obtained in all stages of the process, together with detailed distributions of all the quantities, allows the role of various factors in the formation and development of the combustion sourcr to be elucidated, allows the ignition schememore » and the types of boundary conditions to be easily varied, taking the requirements of the experiment into account, and allows the limits of ignition to be determined.« less