The present numerical study is to investigate the explosive driven behaviors to the flight velocity and flight area of all the fragments of evolvable aimed warhead, and the propagating style of the detonation wave of the three-dimensional model. The results of numerical simulation demonstrate that the dual initiation that one eighth to the end of the axis has the best effect of the five initiation positions. Under the effect of the spherical explosive wave, the directional dispersion of the fragment of the three-dimensional model can be controlled well. The rationality of the numerical simulation was verified by the explosion experiments.

Implicit-explicit additive Runge-Kutta (ARK) methods and 5-th order weighted essentially non-oscillatory (WENO) schemes are employed to simulate on cellular detonation wave propagating through a smooth pipe bend with a 60° bending angle. A detailed elementary chemical reaction model comprised of 9 species and 48 elementary reactions is implemented with a stoichiometric H₂-O₂ mixture diluted with argon. The numerical results show that in the bend, diffraction near the inner wall causes the pressure decrease resulting in both the growth of detonation cell size and detonation failure, but near the outer wall detonation reflection diminishes the cell size. A transition length of about 0.45 m long exists before the detonation regains its regularity after leaving the bend. There are two different modes of reflection due to different turning angles. The transverse detonation waves evolve into a detonation owing to continuous compression by other transverse waves running after at the end of the bend.

Dynamic response of aluminum foam sandwich panel under blast loading was simulated by LS-DYNA3D. Influence of core and face sheets thicknesses of aluminum foam sandwich panels on the deformation and energy absorption was investigated. The core layer compression, the center deflection of the back panel, the energy absorption of core layer and the back panel were obtained. The simulated results can be used to optimize the design of sandwich panels in engineering application.

Investigation of dynamic response of the underground oil storage facility subjected to explosion loads is an important problem. The oil tank can be predigested as a flat-closure cylindrical shell structure. Considering the stress characteres of underground cylindrical shells, the amendatory Winkler model was used to simulate the interaction between cylindrical shell and soil, and a method to determine the related parameters was presented. With the explosion simulation device, a model experiment of underground steel cylindrical shell under explosion loads was completed. An appropriately simplified model of the peripheral explosion loads distribution of the cylindrical shell was assigned according to experimental results. Finete element analysis for the dynamic buckling of flat-closure cylindrical shell was carried out and the critical buckling loads were determined by Budiansky-Roth criterion. Relastionship between critical buckling loads and soil elastic constant K was determined according to the multi-state computation results.

According to the prior uncoupling analysis and utilizing the Rotation-Superposition Method, a large number of numerical experiments for loading cylindrical shells by explosive rods were performed. The average strain difference at three typical locations was defined as the index for evaluating the test simulation fidelity. It was found that the index mainly relies on the ratio of the rods number to the shell radius, i. e. n/r. The relations between the average strain difference and n/r under four conditions, i. e. the normal (ideal) condition, considering incomplete initiations, explosive rod distribution error and non-simultaneous initiations, were obtained. The investigation provides guidelines for the test design and results evaluation.

Based on the critical tube diameter and detonation cell size data in H₂-O₂/Air mixtures, the piston work done model was used to predict their critical energies of direct initiation. The good agreement is found by comparing the theoretical predicted critical energies with those measured in the experiment. Thus, the theoretical model is proved to be able to predict the critical energy of H₂-O₂/Air mixtures within satisfactory. From the theoretical prediction model, it is obviously shown that the critical energy for H₂-Air is significantly bigger than H₂-O₂ mixture when at the same initial conditions. The ZND induction zone length was further investigated to study the large critical energy discrepancy behavior between those mixtures, the results clearly indicated that the induction zone length for H₂-Air is much longer than that of H₂-O₂ mixture at the same initial condition, and it is cube relationship between critical energy and induction zone length, which results in the bigger critical energy of the H₂-Air mixture. This result is in agreement with the critical energy predicted from theoretical model.

The coupled Level Set (LS) method algorithm of medium interface treatment was studied. Advantages and disadvantages of different methods in medium interface treatment process were given by comparing different solution of rotating flow and shearing flow, and the reason is analysed. Particle Level Set (PLS) method and Coupled Level Set and Volume of Fluid (CLSVOF) method are greatly improved in the conservation property of fluid compared on the pure LS through the contrast test. For PLS method, the LS interface can be corrected through reseeding and tracking the particle accurately. For CLSVOF method, the LS function can be reinitialized by reconstructing the interface and transporting the volume. In practical application, the CLSVOF method is more efficient and reasonable, since frequently reseeding will reduce the accuracy and tracking each particle requires more CPU memory for PLS method.

In order to evaluate the influence of shock wave formed by the explosion of cold shock extinguishing bomb on the extinguishing effect, shock wave formed by explosion dispersion of different extinguishing mediums was observed by schlieren experiment apparatus. The propagation law of shock on the interface between air and fluid was studied by numerical simulation, and finally the process of pool fire suppression by cold shock extinguishing system was photographed by high speed photography. Comparative analysis to the percent of high color stage at the same position of each image were made. It was found that the shock wave was formed after extinguishing medium dispersion, but its strength is weak. The mach reflection in the air and disturbance on the liquid surface were found when the shock wave propagated through interface of air and liquid, the strength of shock gradually attenuated with the increase of distance. The percent of high color stage in the earlier stage was weaker than in the later. So the influence of shock wave on the extinguishing effect was weaker than medium dispersion in cold shock extinguishing system.

Focusing on the center shift phenomenon of the coercivity curves and the exchange bias field curves, the dependences of the exchange bias on θ₀, the angle of external field orientation, in ferromagnetic/antiferromagnetic bilayers are studied in the cases that Ψ, the angle between the stress field and the easy axis, is taken as π/4 or π/2. It is shown that the analytical expression of the coercivity cannot be derived by using the Stoner-Wohlfarth model and the principle of energy minimum for the whole range of the angle θ₀. We approximate the coercivity with the switching field for the θ₀ interval at which the principle of energy minimum is not satisfied, and in this way, we got the coercivity expression in the form of piecewise function. Numerical calculations indicate that whether the center shift phenomenon of the coercivity curves and the exchange bias field curves occurs depends on the value of Ψ. While Ψ=π/4, stress results in not only the change of the strength of the effective anisotropic field but the center shift of coercivity curves and the exchange bias field curves; while Ψ=π/2, only the strength of the effective anisotropic field is influenced and no such center shift occurs. The condition in which the center shift of the coercivity curves and the exchange-bias field curves occurs is that θ^*, the angle of the effective anisotropy field to the easy axis, is not equal to zero. In addition, the results also show that the jump phenomenon can only be observed while θ^*≠0, implying that the jump phenomenon is caused by the singularity of the switching field near θ^*.

In order to study the deflagration characteristics of diesel oil ignited by external energy, tests were carried out without any restraints to observe the ignition and explosion process of the oil tank using thermal imager and high-speed camera. Relationship between minimum ignition energy of the diesel oil and ignition location was analyzed. Surface temperature and other parameters of fireballs at different ignition locations were measured and compared. Results show that the fuel explosion of oil tank occurs as two distinct stages: fireball and pool fire. The minimum ignition energy in vapor zone and fuel zone are 45.59 and 307.20 kJ respectively, and the minimum ignition energy is irrelative with ignition location in vapor zone. The maximum surface temperature and area of fireballs depend on the distance between ignition location and the phase interface. Fireballs ignited closest to the phase interface are most potentially dangerous.