摘要:
爆炸冲击波具有鲜明的特征参数,在实验复现时具有难度大、可重复性差的问题。而大型激波管的构建为解决这一问题提供低成本、高效率的实验平台,且能规避小尺度缩尺实验中由于尺寸效应造成的实验结果不准确。应用大型激波管产生不同种类冲击加载的具体驱动方法仍值得深入研究。其中,利用大型激波管氢氧爆轰模拟爆炸波的可行性问题,已由中国科学院力学研究所基于大型激波风洞进行的大量实验研究加以论证,但目前仍然缺乏利用大型激波管直接模拟炸药爆炸冲击波形的研究。因此,进行大型激波管内氢氧爆轰驱动方式下冲击波生成与传播过程的数值模拟研究,并基于模拟研究结果提出在大型激波管内对爆炸冲击波的模拟复现条件。首先,根据现存大型激波设备结构特点,建立具有驱动管、激波整形段和变截面出口特征的大型激波管二维模型。冲击波的生成与传播过程使用含有七步氢氧反应模型的二维非定常粘性可压缩流体控制方程表达,湍流模型选取RNG k-ε模型,并选用二维瞬态耦合式求解器进行数值模拟计算。其次,通过数值模拟计算研究在大型激波管采用氢氧爆轰驱动方式时,驱动初始条件、低反应活性气体掺混、激波管构型等一系列因素对于爆轰形成冲击波波形的影响,并提出其影响规律。最后,选取黑火药爆炸冲击波实验数据作为目标,依据数值计算结果,模拟了大型激波管中冲击波波形调控过程,实现了在大型激波管中利用氢氧爆轰驱动方式对爆炸冲击波的模拟复现。
Abstract:
Blast wave has distinct characteristic parameters, which makes it difficult to replicate in experiments. Large shock tubes provide a low-cost and high-efficiency experimental platform to solve this problem, which can avoid the inaccuracy of the experimental results caused by the size effect in the small scale experiment. The specific driving methods of using large shock tubes to produce different kinds of shock waves are still worthy of further study. The feasibility of using large shock tube hydrogen-oxygen detonation to simulate explosion waves has been demonstrated by a large number of experimental studies based on large shock tunnels conducted by the Institute of Mechanics of Chinese Academy of Sciences. However, there is still a lack of research on blast wave simulation using large shock tubes. Therefore, a numerical simulation study of the generation and propagation process of shock wave generated by hydrogen and oxygen detonation in a large shock tube were conducted, and the reproduction of blast wave in a large shock tube was realized based on numerical simulation. Firstly, based on the designs of existing large shock tubes, a two-dimensional axisymmetric model of a large shock tube with driving tube, shock shaping section and variable angle outlet was established. A two-dimensional unsteady viscous compressible flow governing equations with the seven-steps reaction of hydrogen and oxygen mechanism was used to simulate the generation and propagation process of shock wave. The RNG k-ε model was selected as the turbulence model, and the two-dimensional transient coupling solver was used for numerical simulation. Due to the large scale of the model, turbulence has little effect on the far-field shock wave. Therefore, the finite rate component transport model was selected to couple the interaction between turbulence and chemical reaction, and a two-dimensional transient coupled solver was used. Secondly, with hydrogen and oxygen detonation as the driving method, the effects of initial driving conditions, low chemical reactivity gas mixing, and shock tube configurations on the formation of blast waves were studied. The characteristics of the wave form, the amplitude of the peak pressure and the trend of the positive pressure time were analyzed. Finally, based on the numerical simulation results, the control process of shock wave was simulated in a large shock tube and a good reproduction of the real explosion shock wave in a large shock tube was achieved using hydrogen and oxygen detonation as the driving method.