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.
原子力施設模型(代表長さ0.74 m)内における円筒形アジ化銀(質量10 mg)の起爆により発生した衝撃波の伝播を三次元非粘性圧縮性流体解析し,本研究第1報での実験結果と比較した。まず,解析精度検証として,球状アジ化銀(質量10 mg)の自由空間爆発を一次元球対称解析し,爆風特性を文献値と比較したところ,ピーク静水過剰圧比分布が最大誤差6.2%で一致した。次に,円筒形アジ化銀の自由空間爆発に対し,二次元軸対称解析を実施し,近接場における空気力学的現象を可視化実験画像と比較したところ,衝撃波面,二次衝撃波面,爆発生成気体噴流の噴射方向がほぼ一致した。最後に,実験と同一条件で,模型内での衝撃波伝播の三次元解析を実施した。解析結果の干渉縞画像は,衝撃波面,角部での衝撃波の収束,衝撃波背後で発生する疑似垂直衝撃の成長が実験とよく一致した。また,模型内壁面での過剰圧履歴を比較したところ,(1) 解析結果は実験結果と定量的にほぼ一致したものの,(2) 渦輪を伴う部分,および複数の開口部を通過した後の衝撃波に対しては,高空間分解で解析する必要があり,細密格子や解適合格子が必要である,(3) 爆源近傍で衝撃波が収束する角部では,格子間隔の細化に伴い,実験で得られたピーク静水過剰圧より解析値が大となり,複数格子での処理が必要であること,が示された。