The Spontaneous Ignition of Isooctane Air Mixtures under Steady Flow Conditions 650510
The thermochemical changes occurring prior to spontaneous ignition were investigated for homogeneous mixtures of 2,2,4 trimethylepentane (isooctane) and air in a steady flow apparatus of unique design. Measurements were also made of the ignition times of these mixtures over a range of pressures, temperatures, and fuel-air ratios.
Most of the observable thermodynamic and chemical changes occurred in the last 10–25% of the ignition period. Principal among these changes were thermal decomposition of the isooctane to form isobutylene and probably isobutane; the appearance of significant quantities of propylene, ethylene, methane, hydrogen, carbon monoxide, and carbon dioxide; and a temperature rise of from about 200 to500 F.
Most significant among the results was the observation that the preignition changes for the entire range of conditions tested correlate with a normalized reaction time.