Detangling the detonation of combustible clouds

In a fuel-air explosive, liquid fuel disperses and mixes with air to create a combustible cloud, which begins detonation when it is initiated by a high explosive. The detonation propagation and energy output of this gas-liquid two-phase cloud are linked to certain properties of the cloud, including concentration, particle size, and turbulence. A better understanding of these properties could improve the use of fuel-air explosives in industrial and military applications.

However, the complexity of the detonation process makes it difficult to study. Simin Ren and Qi Zhang developed numerical models to simulate how combustible clouds form and how their detonation progresses when liquid fuel is dispersed under explosion driving load.

They used this method to model the detonation of propylene-oxide clouds generated by the dispersion of 2 kg fuel-air explosives and obtained the distribution of cloud concentration, particle size, and turbulence.

Modeling the clouds at different blast heights also allowed the team to determine how distance from the ground affects detonation temperature and overpressure, which is a sudden post-explosion pressure wave. They found an optimal proportional blast height, at which the detonation temperature range is the largest and the overpressure is the strongest.

“This work can be used in explosion accident prevention and explosion new energy development,” said author Qi Zhang.

Next, the authors will expand the numerical method to study how different fuel and explosion driving loads affect the distribution of the liquid-gas clouds’ concentration, particle size, and turbulence as they form and detonate.

Source: “Near-surface cloud dispersion and detonation propagation law,” by Simin Ren and Qi Zhang, Physics of Fluids (2023). The article can be accessed at https://doi.org/10.1063/5.0141578 .