STP1319

    Fundamentals of Metals Ignition in Oxygen

    Published: Jan 1997


      Format Pages Price  
    PDF (180K) 11 $25   ADD TO CART
    Complete Source PDF (11M) 11 $98   ADD TO CART


    Abstract

    Ignition is associated with the thermal energy input into the system occurring at a rate faster than thermal energy is being lost to the surroundings. The solution of an idealized model for ignition at a plane metal surface characterizes the material in terms of the property thermal inertia, kpc. The thermal inertia for six metals Al, Cu, Fe, Mg, Ni and Ti, at their ignition temperatures is compared to the relative burn resistance of the metals in terms of BRmp, BRbp threshold pressure, resistance to ignition by particle impact and frictional heating ignition, pv. Thermal inertia is in agreement and appears to be suitable property for characterizing metals ignition. In addition, considerations for relaxing the assumptions associated with the idealized model are described and thermal inertia is still a valid characterization for the material.

    The five measures associated with burning do not describe the dynamic system at ignition, nor is the build-up of a condensed product layer addressed by either the ideal model or relaxed model. The effect of this product layer is qualitatively discussed in terms of a Van Heerden diagram for the system. The mechanisms for providing sufficient circulation within the product layer and their representation in terms of dimensionless groups is described. The need for property data and mixing rules (for alloy properties) is pointed out.

    Keywords:

    ignition, thermal inertia, Bond Number, Marangoni Number, steady-states of combustion


    Author Information:

    Wilson, DB
    Consultant, Mesilla Park, NM

    Stoltzfus, JM
    Aerospace Engineer, NASA Laboratories Office, NASA Johnson Space Center White Sands Test Facility, Las Cruces, NM


    Paper ID: STP12059S

    Committee/Subcommittee: G04.92

    DOI: 10.1520/STP12059S


    CrossRef ASTM International is a member of CrossRef.