| Currently, explosion characteristics of large volume fuel air mixtures are difficult and key part of safety science and engneering research. In one way, large volume explosion of fuel air mixtures becomes the significant hazards in civil industry. In another way, study of large volume explosion is the focus for cloud detonation weapon in defence industry. Currently, it is the way that an integrated large volume canister should be split into several smaller parts to improve large volume cloud detonation. This thesis investigates fuel dispersal, cloud detonation and shockwaves interaction process among multiple clouds detonation by using of finite element of numerical simulation and experiment. Where, fuel is filled in a 90° sector canister and an integrated device, including four canisters. The main research results are as follows:(1) According to experiment and numerical simulation, the fuel dispersion process is analysed for a sector canister within a cylindrical center explosive. Defing the exterior direction of arc perpendicular bisector as 0° directions, other directions of 90°, 135° and 180° direnction also would be located by anticlockwise rotation. The results show that: under internal blast load, the first position for shell breakage is 0° direction, with the last of 135° direction appeared in 100 μs. Compared with cylindrical experiment, the radii ratios are 0.59, 0.96, 1.35 and 1.1, respectively at 300 ms for an irregular canister. Based on the above results, a computation equation is put forward for cloud volume. And then the effects of dispersal explosive types, explosive position and groove conditions on shell dynamic response and fuel initial state are analysed.(2) Based on fuel dispersal for the sector canister, an experiment is carried out to study cloud detonation characteristics. The results show that: there are differences among peak overpressure, action time and specifc impuls at four directions. Compared with cylindrical experiment, the maximmun ratio of peak overpressure and correspongding cylindrical value exists as 0.89:0.43:1.68:0.54 among four directions at 8 m. As for action time, it is 0.98:1.62:0.85:1.64 at 15 m. As for ratio impulse, it is 0.68:1.0:0.7:1.56 at 20 m. What is more, the overpressure distribution for single cloud detonation is simulated numerically by multi-material group model. Shockwave isobaric lines are drawn, and that their areas are computed.(3) Based on high-speed cameras and pressures sensors, the experiment is carried out for four sector canisters to search properties of cloud detonation interactions. Four sector canisters are positioned at four symmetry directions respectively. The results show that: multiple blast waves and their interaction traces are monitored by pressure sensors. At the 5 m from central point, peak overpressure, action time and specific impulse are 0.17 MPa, 19.9 ms and 0.87 MPa·ms, respectively, caused by multiple shockwaves interaction. These are much different from single cloud detonation. Based on experimental results, detonation and effect of distance among four clouds are simulated numerically. At the vertical position of 4 m, a high pressure of 1.78 MPa is found, which is higher by 4.9 than the overpressure of single cloud detonation at the same location.The research results shown in this thesis are technical base for research of large volume cloud detonation, including characteristics in cloud formation and its detonation for single sector canister, four clouds detonation and their interactions. These results could not only be a reference for significant accidents prevetion and control in industries, but also have a theoretical guidance for weapon development of large volume detonation. |
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