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Experimental data obtained in this study (Part II) complement the speciation data presented in Part I, but also offer a basis for extensive facility cross-comparisons for both experimental ignition delay time (IDT) and laminar flame speed (LFS) observables.To improve understanding of the ignition characteristics of propene, a series IDT experiments were performed in six different shock tubes and two rapid compression machines (RCMs) under conditions not previously studied. This study is the first of its kind to directly compare ignition in several different shock tubes over a wide range of conditions. For common nominal reaction conditions among these facilities, cross-comparison of shock tube IDTs suggests 20-30% reproducibility (2σ) for the IDT observable. The combination of shock tube and RCM data greatly expands the data available for validation of propene oxidation models to higher pressures (2-40 atm) and lower temperatures (750-1750 K).Propene flames were studied at pressures from 1-20 atm and unburned gas temperatures of 295-398 K for a range of equivalence ratios and dilutions in different facilities. The present propene-air LFS results at 1 atm were also compared to LFS measurements from the literature. With respect to initial reaction conditions, the present experimental LFS cross-comparison is not as comprehensive as the IDT comparison; however, it still suggests reproducibility limits for the LFS observable. For the LFS results, there was agreement between certain data sets and for certain equivalence ratios (mostly in the lean region), but the remaining discrepancies highlight the need to reduce uncertainties in laminar flame speed experiments amongst different groups and different methods. Moreover, this is the first study to investigate the burning rate characteristics of propene at elevated pressures (> 5 atm).IDT and LFS measurements are compared to predictions of the chemical kinetic mechanism presented in Part I and good agreement is observed.

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Using FM spectroscopy formyl radicals were detected for the first time behind shock waves. HCO radicals have been generated by 308 nm photolysis of mixtures of formaldehyde in argon. The HCO spectrum of the (A ˜2A 00 X ~2A 0 ) (09 0 0 00 1 0) transition was measured at room temperature with high resolution and the predissociative linewidths G of the individual rotational lines were fitted to G ¼ X + ZN 02 (N 0 + 1) 2 , where X ¼ 0.22 cm À1 and Z ¼ 1.0  10 À5 cm À1 . Since FM spectroscopy is very sensitive to small line shape variations the spin splitting in the Q-branch could be resolved.Time resolved measurements of HCO profiles at temperatures below 820 K provided the temperature independent rates of reaction ( 4), H + HCO ! H 2 + CO, and reaction (5), HCO + HCO ! CH 2 O + CO,and the low pressure room temperature absorption cross section of the Q( 9)P(2) line at 614.872 nm, a c ¼ (1.5 AE 0.4)  10 6 cm 2 mol À1 (base e).Measurements of the unimolecular decomposition of HCO, reaction (3) HCO + M ! H + CO + M, were performed at temperatures from 835 to 1230 K and at total densities from 3.3  10 À6 to 2.5  10 À5 mol cm À3 . They can be represented by the following Arrhenius expression. k 3 ¼ 4:0  10 13 ÁexpðÀ65 kJ mol À1 =RTÞ cm 3 mol À1 s À1 ðD log k 3 ¼ AE0:23ÞThe corresponding RRKM fit, 4.8  10 17 Á(T/K) À1.2 Áexp(À74.2 kJ mol À1 /RT ) cm 3 mol À1 s À1 (600 < T/ K < 2500), supports the lower range of previously reported high temperature rate expressions.

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