The measurements of laminar burning velocities were performed at LRGP (CNRS-Université de Lorraine) using a heat flux burner adapted from VUB. The apparatus has been modified to the study of gaseous and liquid fuels and allow an increase of the fresh gas temperature up to 398 K. The experimental device has been described previously [33] and [34]. The principle is similar to that used at VUB described above (Section 2.10.2). To allow the investigation of higher initial temperatures, the plenum chamber is encompassed by a thermostatic oil jacket, the temperature of which is set to the desired initial temperature of the unburned gas mixture. The circumference of the burner plate is heated with thermostatic oil set to about 50 K above the temperature of the unburned gas mixture so that the heat gain of the unburned gas mixture from the burner can compensate for the heat loss from the flame to the burner necessary to stabilize the flame.
The burning velocity of propene/air mixtures has been investigated under atmospheric pressure for fresh gas temperature 298 K, 358 K, and 398 K and equivalence ration ranging from 0.5 to 2. The air was considered as a 21/79 vol. oxygen/nitrogen blend. Gas flow rates were measured using Bronkhorst High-Tech Mass Flow Controllers (MFC). Oxygen and nitrogen were delivered by Messer (purity > 99.995%vol.). Propene was provided by Air Liquide (purity > 99.5%, without any noticeable content of other hydrocarbons).
The uncertainty in the laminar burning velocity can be first attributed to the uncertainty in the mass flow measurements (around 0.5% for each MFC) which can lead to a global uncertainty of 1.5% and around 1% in equivalence ratio. The uncertainty in reading the temperature with thermocouples which could lead to an error of around 0.2 cm/s in the laminar burning velocity, and to errors due directly to flame distortions, such as edge effects (estimated around 0.2 cm/s). In the case of very rich mixtures, the change in the curvature of the temperature profile with the gas flow.