电火花作用下粉尘云着火的延迟时间

摘要 为确定粉尘云在电火花作用下的着火敏感性，以钛粉为研究介质，通过以电火花能量释放速率为源项的气-粒两相能量守恒方程建立模型，获得了电火花作用下放电火花能量、粉尘粒径、环境氧体积分数、环境温度及湍流程度对粉尘云着火延迟的影响规律.结果表明:粉尘粒径大小对着火延迟的影响最大，越小的颗粒其着火越迅速;环境温度比室温高50~100K时，粉尘着火延迟时间显著缩短;湍流会加速颗粒间换热速度，缩短着火延迟时间;点火能量与环境氧浓度对着火延迟的影响较小.通过模拟计算扩展了实验研究，也为相关粉尘爆炸预防工作提供理论依据.
Abstract：To investigate the electric spark ignition sensitivity of dust clouds， using titanium powders as a sample， a mathematical model was established based on the gas-particle phase energy conservation equation with spark energy release rate as source phase. The influence of spark energy， particle size， ambient oxygen concentration， ambient temperature and turbulence on the ignition delay of dust cloud was obtained. Results show that particle size has the greatest impact on ignition delay， smaller particle size results in shorter ignition delay. When the ambient temperature is 50~100K higher than the room temperature， the ignition delay time is significantly shortened. Turbulence accelerates the heat transfer rate between particles and shortens the ignition delay time. In addition， the spark energy and the ambient oxygen concentration have little effect on the ignition delay. The calculation is considered as supplement to experimental research as well as theoretical basis for the relevant dust explosion prevention.