J. Phys. IV France 10 (2000) Pr11-155-Pr11-164
Numerical study of shock induced ignition and combustion of CH4-O2-CO2 mixtures in a two dimensional ram acceleratorC. Zhang and S. Taki
Department of Mechanical Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
The numerical simulation for the starting process of the ram accelerator in Hiroshima University (HURAMAC) has being made for almost the same conditions as the experiments, where CH4-O2-CO2 gas mixtures are used. The finite difference method is used for solving the Navier-Stokes equations including chemical reactions in the two-dimensional Cartesian coordinates. At first a test simulation is carried for the case of a cold shot with the same condition of our experiment. The structure of shock waves and the formation of expansion waves are clearly demonstrated. The simulation of a starting process of a hot shot is done for the similar conditions to one of the experiments. Numerical results show that the ignition source is formed just in front of the igniter although another high temperature region appears in the rear area of projectile. The normal shock wave is produced in front of the igniter, then it propagates forwards depending on the combustion heat release. Thermally choking mode is gradually established when the flame propagates whole cross section of the tube with the sabot ejected away from the projectile. The calculated pressure history is compared with the measured one at the middle point of the ignition tube. Very good agreement is found both in the time scale and the pressure amplitude.
© EDP Sciences 2000