Kinetic Modelling of Autoignition of Condensed Hydrocarbon Fuels in Nonpremixed Flows with Comparison to Experiment

摘要

Kinetic modelling studies are carried out to predict critical conditions of extinction and autoignition of condensed hydrocarbon fuels in non-premixed flows. Detailed chemical kinetic mechanisms are employed to describe autoignition. The fuels considered are n-heptane, n-decane, n-dodecane, n-hexadecane, and iso-octane. Critical conditions of extinction and autoignition have been measured previously for these fuels. Steady, laminar, stagnation-point flow of an oxidizer stream, toward the vaporizing surface of a liquid fuel is considered. The oxidizer stream is a mixture of O_2 and N_2. The strain rate at extinction was measured as a function of the mass fraction of oxygen in the oxidizer stream, and the temperature of the oxidizer stream at autoignition was measured previously a function of the strain rate. The experimental data is used here to validate a detailed chemical kinetic mechanism. A key finding of this work is that for the straight-chain alkanes tested here, at a given value of the strain-rate, n-heptane is the most difficult to ignite followed by n-decane, n-dodecane, and n-hexadecane.