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对存在非加热起始段的热平板着火问题进行了理论分析,推导出具有局部相似性的解,并采用基于高活化能假设的匹配渐进展开法进一步得到了理论解.非加热的起始段可以降低气流通过加热段时壁面附近的流速,从而更容易引发着火.结果表明,当常温起始段长度Lx和一般的恒温热平板着火距离xI比值xI/Lx=O(e),此时着火距离xL,I和Lx的平方根成反比.通过数值计算发现,当xI/Lx＜3,局部相似解的误差不超过5％.本文的分析方法可以进一步应用到二维楔形体、三维旋转体边界层等更为复杂边界条件下的着火问题.“,”The problem of thermal-ignition on a boundary-layer at a hot plate with an unheated inlet has been considered,and a local similar solution is derived.An explicit expression for the minimum ignition distance has been derived by using matched asymptotic analysis in the realistic limit of large activation energy.The unheated inlet section can reduce the flow velocity at the boundary-layer of the inlet of heating section,and then lead to easily ignited.It is shown that when the ratio between the length of unheated inlet section Lx and the ignition distance on a isothermal hot plate xI is large enough,the ignition distance xL,I is inversely proportional to the square root of Lx.According to numerical results,the difference between the local similar solutions is less than 5％ when xI/Lx ＜ 3.Although attention in this paper is confined to the flat-plate problem,it should be noted that this analytical method can be applied to more general cases,such as wedge flow ignition problems.