A regime diagram for autoignition of homogeneous reactant mixtures with turbulent velocity and temperature fluctuations

Abstract

A theoretical scaling analysis is conducted to propose non-dimensional criteria to predict weak and strong ignition regimes for a compositionally homogeneous reactant mixture with turbulent velocity and temperature fluctuations. This leads to a regime diagram that provides guidance on expected ignition behavior based on the thermo-chemical properties of the mixture and the flow/scalar field conditions. The analysis extends the original Zeldovich's theory by combining the turbulent flow and scalar characteristics in terms of the characteristic Damköhler and Reynolds numbers of the system, thereby providing unified and comprehensive understanding of the physical and chemical mechanisms controlling autoignition. Estimated parameters for existing experimental measurements in a rapid compression facility show that the regime diagram predicts the observed ignition characteristics with good fidelity.