This work presents the experimental and numerical investigation of premixed and diffusion flame propagation in confined channels. In the case of premixed flame propagation, a constant volume combustion chamber with an aspect ratio of six (6) is used to study the propagation of laminar methane-air flame. This flame undergoes distinct changes in its topology during its propagation. Upon ignition with a spark plug, a spherical flamelet develops which rapidly grows in radius (surface area) and volume. This spherical flamelet grows faster in the axial direction, leading to the formation of a progressively more elongated “finger-shaped” flame. When the side-skirts of the finger flame come in contact with the cold wall, they extinguish and the flame area and flame speed both decrease rapidly. When the side-skirts near the leading edge, the flame flattens to a planar flame. An inward pointing cusp called the “tulip flame” is formed, which retains its topology until it is quenched wither by the cold wall or by collision with a flame that has been ignited on the opposite end. A detailed analysis of the flow-field is performed to study the influence of stagnation points, vortices and other flow features on the structure of the flame.In order to study the propagation of diffusion flames over solid fuel in microgravity conditions, burn tests are usually performed in a drop-tower, to simulate microgravity levels comparable to those in space. Tests of longer duration, which are also cost-effective, can be performed on the earth using a Narrow Channel Apparatus (NCA), where the height of the channel is restricted to minimize or suppress the influence of buoyancy on the flame structure and its rate of propagation. Oxidizer is supplied from the opposite side of the horizontal flame spread and the propagation is recorded using a video camera. The flame spread rate over a slab of Poly-MethylMethAcrylate (PMMA) is quantified for different slab thicknesses and opposed flow oxidizer speeds. The flame spread results obtained from the fourth iteration of Michigan State University’s Narrow Channel Apparatus are compared with those obtained from microgravity tests to be performed at the International Space Station (ISS) in 20143 and will eventually be compared with ISS results in late 2015 or early 2016. The goal is to develop an earth-based testing system (the Narrow Channel Apparatus) that can be used to assess material fire safety for applications in space flight.
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