Method of reconstruction of the chemical composition and combustion efficiency of hydrogen-air mixtures from incomplete experimental data

A principal possibility of approximate reconstruction of the chemical composition in combustion of a hydrogen-air mixture at the end of the scramjet duct from incomplete experimental data (measured concentration of OH radicals and temperature) under the assumption of detailed chemical equilibrium of exchange reactions is analyzed. A closed algebraic system of equations including the concentration of OH radicals and the temperature as parameters is derived in this approximation. A code for solving this system numerically is developed for approximate determination of reaction completeness from the measured temperature and concentration of OH radicals. The model was tested by results of exact thermodynamic calculations of the Jouguet state and overdriven waves in a stoichiometric hydrogen-air mixture and various hydrogen-oxygen mixtures. In the range of pressures of 0.2 to 500 atm and temperatures of 2500 to 3500 K, this method allows the molecular weight and heat release to be reconstructed with accuracy sufficient for gas-dynamic calculations.