可燃固体颗粒堆中的逆向火焰传播

Counter-Current Flame Propagation in a Pile of Combustible Particles

本研究考察了火焰在可燃固体颗粒堆中的传播过程.选取5 mm直径PMMA小球作为特征可燃物,以氧气和氮气的混合气作为氧化剂,在不同氧浓度和流速条件下对火焰传播速度和固体质量消耗速率进行了测量.研究表明,氧通量是影响火焰传播和质量消耗的主导因素.氧通量保持不变时,增大流速会缩短火焰前锋的气相预热长度,使其传播速度降低;同时,固相预热长度拉长导致质量消耗速率升高,使火焰传播速度与质量消耗速率呈现相反的变化趋势.

The flame propagation process in a pile of combustible particles was investigated in this study.The polymethyl methacrylate(PMMA)beads of 5 mm in diameter were used as combustibles and O_(2)/N_(2) mixtures as oxidant.The flame propagation velocity and mass loss rate were measured under conditions with varying oxidant flow rate and oxygen concentration.It was found that oxygen flux was the dominant factor affecting flame propagation and mass loss.For a constant oxygen flux,increasing the flow velocity shortened the gas-phase preheating length of flame front,thereby reducing the flame propagation velocity.Meanwhile,the elongation of solid-phase preheating length led to an increase in mass loss rate.As a result,the flame propagation velocity and mass loss rate showed opposite change trends.