Low-speed Counterflow Flame Experiment in Space for Constructing Unified Theory of Combustion Limits

Abstract

Low-speed counterflow flame experiments will be conducted at Japanese Experiment Module (JEM), Kibo, in the International Space Station (ISS) for constructing unified flammability theory. The subject was selected as an experimental theme in the latter half of the second utilization planning phase of Kibo. This paper presents theoretical background of the present topic and the current progress of experiments and numerical simulations. First, fundamental theories on combustion limits of 1-D planar propagating flames and flame balls are described. Previous works which examined the effects of stretch rate and Lewis number on flames were introduced. The goal of this study is to construct unified theory of combustion limits of deflagration flames and flame balls. Recent microgravity experiments using the airplane, and relevant computations were presented. Both experiments and computations showed the existence of ball-like flames near limits in counterflow field of CH₄/O₂/CO₂ and CH₄/O₂/Xe mixtures.