Combustion of Nitrogen in Low-Pressure H2+O2 and H2+CO+O2 Flames.

摘要

Among other tools, the Air Force employs computer models of the chemistry in afterburning rocket plumes to assess the environmental impact of rocket launches on the upper atmosphere and, in particular, the ozone layer. To improve the accuracy of these models, it is necessary to verify the chemical mechanisms and reaction rate constants used in the models. One method by which verification can be achieved is by comparing the results of laboratory flame measurements with model predictions of combustion products. Nitrogen is present in the atmosphere at all altitudes and is entrained with oxygen into the afterburning exhaust plume of a rocket motor as it rises through the troposphere and lower stratosphere. In the laboratory, we have examined the low-pressure combustion of nitrogen-doped H2 + O2 and H2 + CO + O2 flames. The experiments were carried Out at a pressure of 50 Torr, simulating rocket plume afterburning conditions at 20 km altitude. The cool, post-flame combustion products were analyzed with a mass spectrometer and a specially modified NO(x), chemiluminescence analyzer, as the stoichiometry of the flame was varied to simulate the range of afterburning mixtures encountered in a real rocket plume. Comparisons of the experimental results with preliminary computer flame simulations are used to test the accuracy of the chemical mechanisms employed in modeling nitrogen combustion at low pressures.