Laminar burning velocities and Markstein lengths of propane/
air mixture and propane/methane/air mixture have been
determined and the variations in laminar burning velocity with
equivalence ratio and the mole fraction of methane in fuel mixture
have been studied. The maximum laminar burning velocity of propane/air
mixture is 0.4 m/s and the corresponding equivalence
ratio is 1. With the increase or decrease of the equivalence ratio,
laminar burning velocity decreases. With the equivalence ratio
Fig. 10. Variations of peak pressure and temperature of propane/air mixtures with
equivalence ratio.
Q. Liu et al. / Fuel 140 (2015) 677–684 683increased from 0.7 to 1.5, the Markstein length decreased from
3.8 mm to 0.8 mm, which means the stability of the flame
decrease with the increase of equivalence ratio. For equivalence
ratio of 1, with the addition of methane in propane/air mixture,
the laminar burning velocity of fuel/air mixture decreased from
0.4 m/s to 0.36 m/s, and the Markstein length decreased from
3.63 mm to 0.38 mm, and the stability of the flame decreased.
The uncertainty of the laminar burning velocity and Markstein
length were analyzed and the uncertainty of laminar burning
velocity and Markstein length are less than 10% and less than
20% respectively.
The peak pressure and temperature of a propane/air mixture
have been evaluated as 6.2 bar and 2400 K, respectively. For
propane/air mixtures with an equivalence ratio in the vicinity of
1.8, two explosions take place in the closed vessel. The second
explosion is mainly caused by the rapidly combustion induced by
wall reflection of compression wave. The combustion regime in
propane/air mixture lies between isobaric combustion and
constant volume combustion.