Summary and Unresolved Issues

Work reported here has followed two complementary approaches to characterizing the detonation parameters of certain mixtures of H₂-CH₄-NH₃-N₂O-air. Experiments have been performed with mixtures of H₂-N₂O-O₂-N₂, CH₄-O₂-N₂, CH₄-N₂O-O₂-N₂, NH₃-O₂-N₂, NH₃-N₂O-O₂-N₂, and model tank mixtures of all these. Detonation velocities and cell widths have been measured and reported. Detonation velocities have been found to be very predictable by conventional thermochemical calculations.

Chemical kinetic models of the mixtures of interest have been compared to published experimental data and evaluated with respect to limits of validity. No mechanism has been shown to be valid for all the conditions necessary for detonation modeling, although a modified [Miller and Bowman (1989)] mechanism has been moderately successful. Some correlations between kinetic calculation results and detonation cell widths have been produced from the available cell width data.

Several issues remain unresolved and could benefit from additional attention:

• The performance of the current collection of reaction mechanisms is not as good as desired. More experimental data and validation effort to develop a mechanism specifically for detonation conditions with all the species of interest could make the modeling efforts more robust and reliable.
• The effort to correlate cell width and reaction zone thickness is in its infancy. The key missing element is a physical theory that would suggest a functional relationship between these quantities and other properties of a mixture. In lieu of such a theory, more analysis of the compiled data may uncover further useful relationships.
• The possibility of omitting hydrocarbons or otherwise simplifying the chemical kinetics calculations would dramatically reduce the time necessary to perform these calculations. However, any simplification must be carefully tested before being trusted.