Mean detonation velocity in poorly mixed gas mixtures

A method is proposed for calculating the mean velocity of the front of a plane detonation wave in a poorly mixed mixture of a gaseous hydrocarbon fuel and an oxidizer (oxygen or air). It is assumed that the chemical composition of the mixture exhibits periodic fluctuations in the detonation propagation direction, e.g., owing to gas charge stratification. The method is based on analyzing the functional dependence of the ideal (Chapman–Jouguet) detonation velocity on the molar fraction (normalized molar concentration) of the fuel. It is demonstrated that the mean detonation velocity can be appreciably (by 10–15%) smaller than the ideal detonation velocity. A dependence is found, which allows one to estimate the degree of mixing of the gas mixture on the basis of mean detonation velocity measurements.