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.

Key words: dust explosion, titanium powder, ignition delay time, electric spark, theoretical calculation