Abstract:

In order to further study the detonating effect of UAV, and improve the fire extinguishing efficiency of fire bombs, ANSYS Workbench software was used to establish a finite element model of fire bombs, and the explosion and dispersion process of fire extinguishing agent was simulated to clarify the impact of different detonation heights on the dispersion characteristics of fire extinguishing agent. Meanwhile, full-scale experiments on the vertical dropping of fire extinguishing bombs by unmanned aerial vehicles at different detonation heights were conducted. The results show that the simulation data such as the explosion process of fire extinguishing bomb, the throwing process of fire extinguishing agent and the spreading radius of fire extinguishing agent are in good agreement with the full-scale test results. After the fire extinguishing bomb explodes, the extinguishing agent disperses in the air in a cone shape and spread evenly in the horizontal direction, and the spreading shape is roughly circular. With the increase of detonation height, the landing time of fire extinguishing agent increases, and the horizontal velocity of fire extinguishing agent decreases. The increase of landing time plays a dominant role relative to the decrease of horizontal velocity, resulting in the increase of the spreading radius of fire extinguishing agent with the increase of detonation height. When the detonation height of the fire extinguishing bomb increases from 5 to 12 m, the numerical simulation data of the fire extinguishing agent spread radius increases from 2.04 to 3.56 m, and the error between the numerical simulation data and the experimental data is within 5%.

Key words: fire extinguishing bomb, explosion process, fire extinguishing agent, scattering characteristics, unmanned air vehicle (UAV), numerical simulation, spreading radius