Ignition Behaviors of Pyrolyzed Component and Air near the Lean Limit under Microgravity Condition Available from Parabolic Flights

Abstract

An Experimental setup was designed to conduct ignition experiments for mixtures of the polymethyl methacrylate (PMMA) pyrolyzed gas and air. Suitable ignition methods for microgravity experiments were reviewed, and the laser induced spark ignition was employed to investigate the ignition limit of the mixture. The pyrolyzed gas of PMMA was produced under an emission of the halogen lamp in a vessel filled with nitrogen and air. The gaseous components were sampled and analyzed by a gas chromatograph. Most pyrolyzed component was methyl methacrylate (MMA). Therefore, ignition process of MMA/air mixtures was experimentally investigated under a microgravity condition available from parabolic flights. Ignition tests were performed at 0.1MPa under microgravity and normal gravity conditions. The results indicated that the minimum ignition energy in microgravity decreased compared with that in normal gravity. Initial flame kernel formation and the growth had the preferable direction due to flow fields induced by gravity, resulting in the local quenching phenomena.