Extinction of premixed flames by pressure drops

A theory is developed to explain the experimentally observed extinction of premixed flames by steep pressure drops. The full nonlinear equations are solved numerically and it is found that for large, rapid pressure drops the flame does not recover. This is taken to be clear evidence of extinction. Moreover, it is shown that for slower pressure decreases of the same magnitude recovery occurs. Thus, the rate of the pressure drop as well as its size determines the effect on the flame. An extinction boundary in parameter space is calculated. Numerical studies of an ozone flame including radical reactions are also carried out. Comparisons are drawn between the one-step scheme and the more complicated chemical mechanism. It is found that qualitatively the results correspond but quantitatively the rate of the intermediate reactions are important.