A model for detonation cell size prediction from chemical kinetics

A correlation between characteristic reaction zone widths, calculated from detailed chemical kinetic models, and experimentally measured or numericall y simulated detonation cell sizes is analyzed. An approach is proposed to g eneralize such a correlation, taking into account the multidimensional stru cture of real detonations. It is based on the characteristic reaction zone width, delta, calculated at initial conditions that are representative for a multidimensional detonation wave. The ratio, A, of the detonation cell wi dth, lambda, to the characteristic reaction zone width delta is considered to be a function of two stability parameters (dimensionless effective activ ation energy and a parameter describing the relation between chemical energ y and initial thermal energy of the combustible mixture). This approach is evaluated against experimental data and results of multidimensional calcula tions. The resulting semi-empirical correlation is suggested to describe th e dependence of the lambda/delta-ratio on the stability parameters. This gi ves a basis for the prediction of detonation cell widths from detailed chem ical kinetic calculations over a wide range of mixture compositions and ini tial conditions. (C) 1999 by The Combustion Institute.