Volume 6, Issue 6 (June 2009)

    The Rate-Limiting Mechanism for the Heterogeneous Burning of Cylindrical Iron Rods

    (Received 8 December 2008; accepted 1 May 2009)

    Published Online: 2009

    CODEN: JAIOAD

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    Abstract

    This paper presents the findings of an investigation into the rate-limiting mechanism for the heterogeneous burning in oxygen under normal gravity and microgravity of cylindrical iron rods. The original objective of the work was to determine why the observed melting rate for the burning of 3.2-mm-diameter iron rods is significantly higher in microgravity than in normal gravity. This work, however, also provided fundamental insight into the rate-limiting mechanism for heterogeneous burning. The paper includes a summary of normal-gravity and microgravity experimental results, heat transfer analysis, and post-test microanalysis of quenched samples. These results are then used to show that heat transfer across the solid/liquid interface is the rate-limiting mechanism for melting and burning, limited by the interfacial surface area between the molten drop and solid rod. In normal gravity, the work improves the understanding of trends reported during standard flammability testing for metallic materials, such as variations in melting rates between test specimens with the same cross-sectional area but different cross-sectional shape. The work also provides insight into the effects of configuration and orientation, leading to an improved application of standard test results in the design of oxygen system components. For microgravity applications, the work enables the development of improved methods for lower cost metallic material flammability testing programs. In these ways, the work provides fundamental insight into the heterogeneous burning process and contributes to improved fire safety for oxygen systems in applications involving both normal-gravity and microgravity environments.


    Author Information:

    Ward, Nicholas R.
    School of Engineering Systems, Queensland Univ. of Technology (QUT), Brisbane, Queensland

    Steinberg, Theodore A.
    School of Engineering Systems, Queensland Univ. of Technology (QUT), Brisbane, Queensland


    Stock #: JAI102269

    ISSN: 1546-962X

    DOI: 10.1520/JAI102269

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    Author
    Title The Rate-Limiting Mechanism for the Heterogeneous Burning of Cylindrical Iron Rods
    Symposium Twelfth International Symposium on Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres, 2009-10-09
    Committee G04