Experimental evaluation of vibration-dissociation coupling models

The coupling between the vibrational relaxation process and dissociation process in nitrogen is studied using a computational fluid dynamics method. The conservation of vibrational energy equation is derived and the form of the source terms is determined for all physically consistent coupling models. The results from three current coupling models are compared to existing experimental results for spherical geometries. It is found that the coupling models of Park, Treanor and Marrone, and Macheret and Rich are able to accurately predict the shock stand-off distances and density contours for these conditions. The differences among the models in the amount of vibrational energy removed with dissociation produces differences in the vibrational temperature profiles, however. Computational results show that wedge geometries are more sensitive to the differences between the models. These results are being used to design new experiments which will be more sensitive to the choice of vibration-dissociation coupling model.