摘要
鉴于目前对障碍物交错阵列内爆燃转爆轰(deflagration-to-detonation transition,DDT)现象的认识不足,采用高精度算法和动态自适应网格求解完全可压缩反应性Navier-Stokes方程,对不同障碍物间距条件下方形障碍物交错阵列内预混氢-空气DDT引发过程进行数值模拟研究。结果表明:减小障碍物间距有利于在火焰加速前期增加火焰面积、后期增强激波压缩未燃气体,从而缩短DDT时间和距离。然而,当障碍物间距减小至某阈值时,会出现结巴式爆轰,使DDT距离增加。DDT主要由障碍物前壁的反射激波与火焰相互作用引起。爆轰绕过障碍物时发生局部解耦,然后与壁面或来自障碍物另一侧的激波和失效爆轰波碰撞时可能引发爆轰再起爆。若障碍物间距太小,激波强度随爆轰的解耦而衰减严重,易导致爆轰失效。方形障碍物交错阵列比圆形更易引发DDT,因前者可在垂直和平行于火焰的传播方向产生反射激波,有助于激波作用于火焰和未燃气体。
Study on gas deflagration-to-detonation transition(DDT)is of great significance for the research and development of industrial explosion prevention and detonation propulsion technology.Staggered array of obstacles is a typical obstacle layout that may be involved in the gas ignition and explosion scenario.Its existence usually significantly promotes the occurrence of DDT.In view of the lack of understanding of DDT in staggered array of obstacles,high-precision algorithm and dynamic adaptive grid were applied to solve the two-dimensional,fully compressible reactivity Navier-Stokes equations coupled with a calibrated chemical-diffusive model.Numerical investigation on the initiation process of DDT of premixed hydrogen and air in staggered array of square obstacles under different obstacle spacings was carried out.The results showed that decreasing obstacle spacing is beneficial to increase flame surface area in the early stage of flame acceleration and enhance compression of unburned gas by shock wave in the later stage,thus shortening DDT run-up time and distance.However,when the obstacle spacing is reduced to a threshold value,stuttering detonation occurs and the DDT run-up distance increases.The occurrence of DDT is mainly caused by the interaction between the flame and the shock wave reflected from the front wall of obstacle.The detonation partially decouples when it diffracts around an obstacle.Detonation re-initiation may be triggered when the decoupled detonation collides with a wall or with the shock wave or failure detonation wave from the other side of the obstacle.If the obstacle spacing is too small,the shock wave intensity decays significantly during detonation decoupling.This can easily lead to detonation failure.In addition,shock waves can be reflected off the staggered array of square obstacles in the vertical and parallel directions to the flame propagation direction,which help shock waves to act on the flame and unburned gas mixture.Therefore,DDT is more likely to be initiated in the staggered array of square obstacles than that of circular obstacles.
作者
李敏
肖华华
LI Min;XIAO Huahua(State Key Laboratory of Fire Science,University of Science and Technology of China,Hefei 230026,Anhui,China;Anhui Province Key Laboratory of Special Welding Technology,Huainan 232063,Anhui,China)
出处
《爆炸与冲击》
北大核心
2025年第11期1-12,共12页
Explosion and Shock Waves
基金
国家自然科学基金(12302449)
安徽省自然科学基金(2308085QE170)
特种焊接技术安徽省重点实验室开放基金(2023SW1002)。
关键词
爆燃转爆轰
火焰加速
激波
障碍物阵列
氢气
deflagration-to-detonation transition
flame acceleration
shock wave
obstacle array
hydrogen
