Research on the Explosion Temperature Response of Fuel Air Explosive Measured by Colorimetric Pyrometer

An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.

Quantitative Method of the Structural Damage Identification of Gas Explosion Based on Case Study:The Shanxi “11. 23” Explosion Investigation

In order to present a retrospective analysis of exposition accidents using input data from investigation processes,data from a specific accident was examined,in which we analyzed possible involved gas species（ liquefied petroleum gas; nature gas） and computed their concentrations and distributions based on the interactions between the structures and the effects of the explosion. In this study,5 scenarios were created to analyze the impact effect. Moreover,a coupling algorithm was put into practice,with a practical outflow boundary and joint strength are applied. Finally,the damage effects of each scenario were simulated. Our experimental results showed significant differences in the 5 scenarios concerning the damage effects on the building structures. The results from scenario 3 agree with the accident characteristics,demonstrating the effectiveness of our proposed modeling method. Our proposed method reflects gas properties,species and the concentration and distribution,and the simulated results validates the root cause,process,and consequences of accidental explosions. Furthermore,this method describes the evolution process of explosions in different building structures. Significantly,our model demonstrates the quantatative explosion effect of factors like gas species,gas volumes,and distributions of gases on explosion results. In this study,a feasible,effective,and quantitative method for structure safety is defined,which is helpful to accelerate the development of safer site regulations.

Experiment and Calculation for Expansion Process of Ablation Plasma Jets in Liquid

The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands in the axial and radial directions simultaneously, and then, is subjected to the constraint of chamber wall, in axial direction mainly. The maximum axial speed of the cavity's head ranges from 240m/s to 280m/s. Some strong heat conduction and mass transmission effects can be found in the surface of Taylor cavity, where the plasma cools down and condenses as solid particles while the liquid vaporizes as gas. Compared the expansion processes of the cavities among the different discharge energies and the nozzle diameters, it can be seen that the expansion speed of the cavity is directly proportional to the discharge energy and inversely to the nozzle diameter, and the effect of the discharge energy is stronger than that of the nozzle diameter. A set of equations describing the expansion process of ablation plasma jet was derived under the assumption of momentum conservation. The calculated results by use of the equations coincide with the experimented results better.

Residual Characteristic of High-Velocity Steel Fragments Penetrating UHMWPE FRP Laminates

The mechanical performance of ultra-high molecular weight polyethylene fiber (UHMWPE) and its composites were proposed. Penetrated properties of different thicknesses UHMWPE FRP laminates (URP) impacted by 3.3g cubic high velocity fragments were studied. According to the ballistic experimental results and theoretical analysis, the linear relation between ballistic limit vBL and area density AD was confirmed. The relative parameters of showing experientially residual velocity vr were expressed by the function of AD. In the end, versatile experiential expression between vr and AD was found. Prediction of vr and vBL using obtained expressions under the above stated condition of impacting URP was consistent with the experimentaled results. Consequently, the two experiential relations can be used to predict the residual velocity and ballistic limit of cubic high velocity fragments impacting URP. The residual characteristic of high-velocity steel fragments penetrating UHMWPE FRP laminates can be more exactly forecasted by the two derived experiential formulas.

Propagating Characteristic of Premixed Methane-Oxygen Deflagration in the Coal Mine Lane Including a Refuge Chamber

In order to investigate detonation propagation and distribution problems of premixed CH_4 ＋ 2O_2 mixture around a concrete structure such as a refuge chamber,detonation experiments in one small size tube were conducted. A simulation method was developed to obtain the flow field load distribution in the coal mine lane and pressure load of each part for the refuge chamber. Firstly,a physical model of a full-size explosiontest lane was established,which included the refuge chamber. With the calculations of the exact initial detonation pressure,the propagation characteristics of CH_4 ＋ 2O_2 premixed mixture detonation in the lane was simulated. Simulation results of various parts from AUTODYN are recorded,and the shock wave arrival time and the pressure peak can be observed from the detonation pressure-time curve over the changing propagation distance. So curve differences in different locations cannot be ignored. Then by detonation experiments in the small size tube,detonation pressure-time curves and velocity were obtained. Finally the simulation waveform of variation curve agreed well with the experimental results,which validated the detonation simulation method. The difference between shockwaves of the two sensors confirmed that detonation wave changed along with distance and time. These results should be taken into serious consideration for the detonation progration and distribution problem in future researches.