Laminar burning velocity measurements of iso-octane + air mixtures at higher unburnt mixture temperatures

摘要

Surrogate fuels offer an effective and efficient alternative in predicting the combustion characteristics of various practical fuels such as gasoline, kerosene and diesel. Once standardized, the chosen constituents of the surrogate fuels help reduce the complexity involved in the development of detailed kinetic models for engine simulations at global scales. In this study, with air being the oxidizer, iso-octane as a surrogate constituent of the gasoline fuel is used for measuring the laminar burning velocities at high mixture temperatures. Present investigations report LBV measurements for a temperature range of 300-640 K using an externally heated diverging channel (EHDC) method. The comparison is then carried out with the available experimental data in the literature and kinetic model predictions at 1 atm pressure for an equivalence ratio range of phi = 0.7-1.4. Temperature exponent, (alpha) is derived using the power-law correlation and a good consistency is observed between the current measurements and the kinetic model predictions of LLNL-V3 (2008) and Hasse (2000) for a temperature ratio of 1.7 and 1.8 respectively. Reaction pathway analysis exhibits that the presence of species TC3H6 CHO at 470 K leads to a lower LBV than at 640 K. Methyl radical, CH3 plays a significant role in the auto-ignition phenomena as highlighted from the sensitivity analysis at phi = 1.1. The present study also becomes vital in terms of improving the detailed kinetic models targeting the prediction of knocking propensity.