Detonation Initiation in H{sub}2-Air and CH{sub}4-Air Mixtures by Incident Shock Wave - One-Dimensional Numerical Simulation

摘要

Detonation processes in gas mixtures for a long time have been an object of interest of many scientists studying combustion processes. This paper is the contribution to expanding growth of numerical investigations in detonation processes and increasing knowledge of physical aspects of this phenomenon. This paper presents detailed analysis of one-dimensional model of shock initiation of detonation wave. Two combustible mixtures hydrogen-air and methane-air were taken under consideration. Hydrogen-air mixture was analyzed with different concentration of hydrogen, from rich to very lean and with two Mach numbers of strong incident shock wave. The analysis of the transition to detonation process was performed for a bursting diaphragm experiment. In the presented simulation, an increase of Mach number of incident shock wave was made by releasing chemical energy in the driver section at the moment of bursting of the diaphragm. The hot gas in the driver section and fuel mixture in the shock tube is separated by inert gas section. The physical model deals with Euler conservation equations, using an ideal gas law. The set of conservation equations was integrated numerically with the FCT method. The heat release mechanism bases on integration of detailed chemical kinetics equation with the use of CHEMKIN package. Results of the investigation include distribution of thermodynamic and flow parameters in respective time sequence from hot spots formation to detonation relaxation, including collision of retonation wave and contact surface. The main events occurring in the shock tube simulation are also presented on position-time diagrams.