The non-isothermic three-variable chemical model of the oscillatory combustion of NH~4ClO~4+Mg+K~2Cr~2O~7 system is established in the present paper. The nonlinear reaction kinetic character of this system is described by the results of numerical simulation. By applying mathematical methods for nonlinear analysis, the mechanism of the nonlinear chemical kinetics of the solid phase combustion is studied. The results show that the system has rich content of the character of the nonlinear chemical kinetics. From the result of numerical simulation it can be seen that with the changing of the value of the nondimensional variable μ of NH~4ClO~4 when μ is between μ=0.00547863 and μ=1.47185, the oscillatory period is different. When μ=0.5678, 0.591, 0.6378, 0.6388 and 0.6478, the period -1, period -2, period -4, pseudo-period and period -3 oscillations are obtained respectively. It can be recognized that the change of NH~4ClO~4 has influence on the oscillatory period. The result of numerical simulation is same to the reaction mechanism analysis of the experimental study. The non-isothermic three-variable chemical model studied in the paper not only considers the influence of concentration on the oscillatory period, but also analyzes the effect of temperature on the oscillatory combustion. The nonlinear numerical analysis method is combined with the chemical kinetics reaction mechanism analysis of the pyrotechnics combustion in the present paper. And the experimental and chemical models study are developed.

Key words: AMMONIUM PERCHLORATE, MAGNESIUM, POTASSIUM DICHROMATE, REACTION KINETICS, REACTION MECHANISM, CHEMICAL OSCILLATIONS, NUMERICAL SIMULATION