火灾环境下火焰包覆厚度对DNAN炸药热响应特性影响的数值模拟研究

Numerical simulation study on thermal response characteristics of DNAN explosive under different flame coating thickness in fire environment

为获得火灾环境下火焰包覆厚度对弹药热响应特性的影响规律,针对火焰辐射热流的主控影响机制——火焰包覆厚度,综合考虑了弹药内部空气夹层复合传热效应以及炸药高温热分解放热效应等因素,建立了可用于预测不同火焰包覆厚度下弹药热响应特性的数值模型及计算方法,对不同火焰包覆厚度下典型弹药模型的热响应特性开展了数值模拟研究。结果表明:火焰辐射率和辐射热流会随火焰包覆厚度的增加而增加。随火焰包覆厚度的增加,弹药的温升呈非线性增加,温升速率也随之增加。点火延滞时间则随火焰包覆厚度的增加而减小,当火焰包覆厚度L<1 m时,点火延滞时间随火焰包覆厚度增加呈非线性减小;当火焰包覆厚度L≥1 m时,点火延滞时间逐渐趋于恒定值。因此,在火焰包覆厚度L<1 m时,需考虑火焰包覆厚度大小对弹药热响应特性的影响。

To investigate the influence of flame coating thickness on the thermal response characteristics of ammunition in a fire environment,focusing on the primary controlling mechanism of flame radiative heat flux,namely the flame coating thickness.The composite heat transfer effect of the internal air layer in ammunition and the heat release effect of high-temperature explosive decomposition were comprehensively considered.A numerical model and computational method were developed to predict the thermal response characteristics of ammunition under different flame coating thicknesses.The thermal response characteristics of typical ammunition models under different flame coating thicknesses were simulated.The research results indicate that flame radiance and radiative heat flux increase with increasing flame coating thickness.As the flame coating thickness increases,the temperature rise of the ammunition shows a non-linear increase,and the temperature rise rate also increases.The ignition delay time decreases with increasing flame coating thickness.When the flame coating thickness L<1 m,the ignition delay time decreases non-linearly with the increase of flame coating thickness.When the flame coating thickness L≥1 m,the ignition delay time gradually tends to a constant value.Therefore,the impact of flame coating thickness should be fully taken into account in the thermal response of ammunition when flame coating thickness L<1 m.