Investigation for Study of Complex Chemical Equilibrium of Combustion Products Gas Mixture

Complex chemical equilibrium usually occurs at severe conditions in which experimental measurements are very difficult. Therefore, in order to obtain accurate theoretical results, attention had been directed to investigate the existing methods, and to modify the most suitable one to give accurate results. This work included both theoretical analysis and experimental work.In the theoretical analysis, an adequate method for calculating chemical equilibrium in a predominantly gaseous, multi-component reactive mixture was investigated and successfully applied. This method involved the minimization of Gibbs free energy, in which the expected reaction products are stated. First the formation of chemical species, of which concentrations prevail in the mixture, then the formation of the gaseous atomic species by dissociation of previous ones, and finally, the formation of complex chemical species from the atomic species. A computer program, which permits calculation of equilibrium compositions by the NewtonRaphson iteration procedure, and Gauss elimination technique,has been developed.The program contains a data base file, in which the newer thermodynamic properties of reactants and all expected products are listed.The program also calculates theoretical rocket motor performance using both theoretical and recent empirical equations.  An experimental solid propellant rocket motor was designed and subjected to static testing. Two types of propellants, double base propellant and composite propellant, were examined with different compositions for each type. A set of fourteen experiments was successfully conducted (nine experiments using double base propellants, and five using composite propellants).The Results of the calculations have been compared with those obtained from the experiments and with those published by NASA. The comparison gave satisfactory agreement (Average deviation = 5% for the experiments, and = 4% for NASA). Thus, the program can be used, with confidence, to obtain either complex chemical equilibrium composition and/or rocket motor performance.