扰动作用下爆轰形成机理  

Mechanisms of Detonation Initiation under the Effect of Perturbation

作　　者：张静雯[1] 彭澳 陈先锋[1] 孙绪绪 ZHANG Jingwen;PENG Ao;CHEN Xianfeng;SUN Xuxu(School of Safety Science and Emergency Management,Wuhan University of Technology,Wuhan 430070,Hubei,China)

机构地区：[1]武汉理工大学安全科学与应急管理学院,湖北武汉430070

出　　处：《高压物理学报》2022年第6期52-61,共10页Chinese Journal of High Pressure Physics

基　　金：国家重点研发计划(2021YFB4000901);中央高校基础研究项目(223161001);中国民航大学民航热灾害防控应急重点实验室开放基金(RZH2021-KF-05);中国科学技术大学火灾科学国家重点实验室开放基金(HZ2022-KF09)。

摘　　要：为详细研究扰动作用下爆轰触发机理,在内径为90 mm的圆管内用阻塞比为0.923的孔板使稳定爆轰完全失效,然后在孔板下游0.5 m处安装一个由直径为2 mm的圆柱杆构成的小型障碍物,用以研究人为添加的小扰动对不稳定爆轰触发的影响。通过改变小型圆柱杆的数量(1、2、3),得到了3种不同类型的小扰动,其阻塞比分别为0.03、0.04和0.07。采用PCB压力传感器记录爆轰波的到达时间,以获得爆轰平均传播速度,同时采用烟熏板技术记录爆轰胞格结构。实验结果表明:小扰动可显著促进爆轰起爆,爆轰触发临界压力从光滑管道内的37 kPa降低到25 kPa;小扰动还增强了波阵面的不稳定性,诱导形成局部爆炸点,这是导致爆轰触发的重要原因;在极限条件下,爆轰触发条件可近似量化为D_(H)/λ>1(D_(H)为水力直径,λ为爆轰胞格尺寸)。采用忽略黏性的二维欧拉方程作为控制方程,两步诱导反应速率模型描述化学反应过程,模拟研究了扰动波长和振幅对爆轰触发的影响。数值模拟结果表明,低振幅、高频率的扰动可诱导产生更多的横波增强波阵面的不稳定性,有助于爆轰触发。This paper aims to experimentally and numerically investigate the effect of perturbation on the detonation initiation.In a round tube with 90 mm inner diameter,a stable detonation is firstly failed by an orifice plate with the blockage ratio of 0.923,and then the small-scale perturbation created by a cylindrical obstacle with a 2 mm diameter is introduced to a position 0.5 m downstream of the orifice plate to study the role of the perturbation on detonation re-initiation.Three different obstacles with blockage ratio of 0.03,0.04 and 0.07 can be obtained by changing the number of the cylindrical obstacles equal to 1,2 and 3.PCB gauges are used to record the time-of-arrival of the detonation,from which the detonation speed can be calculated.The smoked foil technique is used to record the cellular structures.The experimental results indicate that the small-scale perturbation can significantly facilitate the detonation initiation,and the critical pressure can be decreased from 37 kPa to 25 kPa in the smooth tube.By analyzing the cellular structures,it can be found that the perturbation can enhance the cellular instability inducing the local explosion centers,which is the main reason causing the detonation initiation.Near the limit,the detonation initiation mechanism can be approximately quantified as DH/λ>1,where DH is hydraulic diameter andλrepresents the cell size.In the simulation,the reactive Euler equations are used as the governing equations and two-step induction-reaction rate law is considered.The numerical results indicate that the disturbance with lower wavelength and amplitude can induce more transverse waves and enhance the cellular instabilities,facilitating the detonation initiation.

关 键 词：扰动 爆轰触发 不稳定性 振幅 波长 

分 类 号：O381[理学—流体力学]