Numerical Studies On Three-dimensional Explosion Flow Field And Dynamic Responses Of Explosion Vessel

This paper presents the solutions of the two main problems: explosion of the condensed high energy explosives and the fluid-structure interaction with impacts. The main difficulties are how to deal with the expansion of explosion gas products in state of high pressure and temperature, and the interaction of blast waves and structural responses. The former essentially is associated with the problem of interface with big pressure/density proportion and the multi-media tracking or capturing. This is one of the current main problems in computational fluid dynamics. The later is involved with the accurately obtained pressure close to structure for structural analysis. Since explosion field and structure deformation are coupled on boundaries, we have to solve these problems systematically. To setup a 3-d numerical analysis platform, we have conducted the studies listed below:1) Chapter 1 introduces the background and the progress of related works, at the end of this chapter, we have noted the characteristic of this investigation.2) Chapter 2 gives a brief description of the problem and the state equations. This chapter introduces the reaction mode, the governing equations, the interface capturing method employed in this work in great detail. Moreover, the non-dimensionalization and the initial conditions as well as boundary conditions were presented. To get the detonation process of explosives, Euler equations with source terms were used. As a simplified method, dot-explosion self-similar solution was also adopted in the computation, which omitted the detonation process. The interface of gas products and ambient air was tracked with the levelset function. ALE (Arbitrary Lagrangian Eulerian) equation was established to obtain the explosion field while the principle of virtual work was used to obtain the structural responses.3) Chapter 3 presents the numerical methods used to solve the equations given in chapter 2. PPM (Piecewise Parabolic Method) scheme was of 3rd order accuracy used to solve ALE equations in finite volume method. Finite ele- ment method was used to solve the principle of virtual work, Newmark method was adopted in time integration. Levelset equation was solved by the 5th order WENO scheme, and so did the reaction rate equation. The 4th order Runge-Kutta method was chosen to solve the ODE (Ordinary Differential Equation) derived from 1-d spherical Euler equations. Some typical problems were chosen to check the codes.4) Numerical results are obtained by applying the validated codes to simulate the typical tests. It was shown that our codes have successfully solved the problem of explosion products expansion to air. The given figures have clearly shown the ignition and detonation growth, the blast wave propagation, the fluid-structure interaction processes and the deformation of structures, etc. The results are also in consistent with the experimental data reported. At the end, causes of calculation errors are discussed.5) Conclusions and suggestions to the future work are given in the final chapter of this paper.