WANG Qi, ZHI Xiaoqi, XIAO You, HAO Chunjie. Analysis of the effect of a venting structure on slow cookoff of Comp-B based on a universal cookoff model[J]. Explosion And Shock Waves, 2022, 42(4): 042301. doi: 10.11883/bzycj-2021-0253
Citation:
WANG Qi, ZHI Xiaoqi, XIAO You, HAO Chunjie. Analysis of the effect of a venting structure on slow cookoff of Comp-B based on a universal cookoff model[J]. Explosion And Shock Waves, 2022, 42(4): 042301. doi: 10.11883/bzycj-2021-0253
WANG Qi, ZHI Xiaoqi, XIAO You, HAO Chunjie. Analysis of the effect of a venting structure on slow cookoff of Comp-B based on a universal cookoff model[J]. Explosion And Shock Waves, 2022, 42(4): 042301. doi: 10.11883/bzycj-2021-0253
Citation:
WANG Qi, ZHI Xiaoqi, XIAO You, HAO Chunjie. Analysis of the effect of a venting structure on slow cookoff of Comp-B based on a universal cookoff model[J]. Explosion And Shock Waves, 2022, 42(4): 042301. doi: 10.11883/bzycj-2021-0253
In order to study the influence of the venting structure on the ignition time and the internal physical field changes before thermal ignition of melt cast explosives, slow cookoff tests with multi-point temperature measurements were designed for two groups of ammunitions with or without a venting structure. The area of the venting hole was designed to meet the requirements of the pressure balance method for the critical cross-sectional area. The temperature-time curves of the two ammunitions heated at a rate of 3.3 ℃/h were obtained through the tests. The opening time of the venting hole was determined. It was found that venting led to a decrease in the internal temperature of the explosive and delayed the ignition time. A universal cookoff model (UCM), including the buoyancy-driven flow after the explosive melt and the variation of the decomposition rate with pressure and reaction process, was applied to the cookoff simulation of Comp-B. In the simulation, the ammunition without a venting structure was considered to be sealed during the cookoff process. The opening time of the venting hole for the ammunition with a venting structure was determined based on the test. After the venting hole was opened, the ammunition was considered to be fully ventilated, and the decomposition rate of the explosive reduced. The variations of the temperature field and internal pressure of the ammunitions with or without a venting structure during the cookoff process were simulated. The results show that under the slow cookoff condition, the internal pressure of the ammunition increases slowly at first and then sharply. The pressure change trend of the ammunition with a venting structure is the same as that without a venting structure. The action of the venting structure will suddenly reduce the decomposition rate of the explosive, and then the internal temperature decreases. The decrease in the decomposition rate and the product bubbles-driven convection lead to a delay in the ignition time. Due to the convection, the ignition points of the explosives are all in the top area.
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