Science and Technology of Energetic Materials

Vol.66, No.1 (2005)


Experimental simulation of large-scale explosion using a micro-charge explosion (II)
- Numerical study on shock waves propagation starting from detonation wave propagation in explosive - (*in Japanese)
Toshiharu Mizukaki and Kazuyoshi Takayama


In order to investigate the characteristics of the shock waves propagated in complicated-closed space, three-dimensional non-viscous compressible fluid analysis was examined on a 10 mg cylindrical-shaped Silver-Azide pellet explosion in the scaled model of a nuclear facility with representative length of 0.74 m. The results were compared with the experimental ones of the previous report. First, in order to evaluate accuracy of the calculation, explosion with a 10 mg spherical Silver-Azide in free-space was analyzed and compared with a literature. The results showed good agreement with the literature on the distribution of peak overpressue ratio with error up to 6.2 %. Next, the early stage of explosion with a 10 mg cylindrical-shaped Silver-Azide was calculated by two-dimensional axisymmetric analysis. Aerodynamic phenomena generated by the explosion were compared with pictures visualized by direction-indicating color schlieren method. The results also agreed with schlieren pictures on shock front, secondary shock wave, and the direction of explosion-product jet. Finally, we tried to calculate three-dimensionally the propagation of shock waves inside the scaled model under the identical condition of the experiment described in the previous report. Interferograms generated by the numerical results showed good agreement with the interferograms obtained by the experiment. The comparison of overpressure profiles between experimental and numerical indicated that: (1) the numerical results achieved quantitative agreement, (2) fine-mesh or adaptive mesh must be needed to analyze both phenomena with micro-structure such as vortex rings and after being propagated through plural open-wall, (3) due to smaller space of analytical mesh than sensor surface of the pressure transducer used in the experiment, numerical analysis at the corner nearby explosion center tends to indicate larger overpressure ratio than which experiment gives. Therefor, an average of the value of plural mesh on the surface must be done after analysis.

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