Revealing Impact Characteristics of the Cassava Dust Explosion Process: Experimental and Numerical Research

The combustion and explosion characteristics of cassava starch and the dispersive physical motion law of dust were systematically studied using a 20 L (=0.02 m(3)) spherical explosive test device and the numerical simulation method. The experimental results show that the explosion pressure first increases and then decreases with increasing ignition delay time, dust concentration, and spray pressure in the dust storage tank. The maximum explosion pressure was obtained with a dust concentration of 750 g/m(3), while the maximum rate of pressure increase was obtained when the concentration was 250 g/m(3). The calculated maximum explosion index was 22.3 MPa center dot m center dot s(-1). The simulation results show that the physical movement law of the dust was as follows: high initial velocity -> gradual decrease in diffusion velocity -> upward linear movement of dust -> outward diffusion motion -> continuous disorder motion -> free settlement -> gradual reduction and disorder state -> finally, complete settlement. With a powder diffusion time of 120 ms, the dust distribution in the round sphere was the most uniform, which was consistent with the experimental results. After dust ignition, the temperature first gradually increased and then decreased due to heat dissipation. The maximum pressure in the vessel was 46.7 MPa, and the turbulence was the most intense close to the ignition point.