Underwater implosion mechanism of PMT area reduction equivalent model
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摘要: 光电倍增管(photomultiplier tube，PMT)是中微子探测器的核心部件，是由玻璃材料制成的内部真空的薄壳结构，排列在深水中工作，若一个PMT被压溃会产生内爆冲击波，会引起周围PMT发生殉爆。针对PMT内爆，建立了PMT内爆数值计算简化模型，并将计算与试验结果进行对比，验证简化模型的合理性。在此基础上，提出了基于面积折减等效模型的PMT内爆计算方法，通过等效模型分析了防护装置破口面积对PMT内爆的影响，得出随着防护装置破口面积的减小，水流碰撞发生PMT内爆的时刻相应提前，内爆产生的冲击波脉宽基本保持不变，冲击波压力峰值明显减小。该研究有利于找到有效的PMT内爆防护方法。Abstract: The photomultiplier tube (PMT) is the core component of the neutrino detector. It is a thin shell structure made of glass material with a vacuum inside and arranged to work in deep water. Once the PMT is crushed, it generates a strong shock wave, which will cause a blast of the surrounding PMT. Aiming at the implosion of PMT, a simplified simulation model of PMT implosion was established, and the simulation results were compared with the experimental results to verify the rationality of the simplified model. On this basis, the PMT implosion calculation method was proposed based on the area reduction equivalent model, the influence of the breach area of the guard on the PMT implosion was analyzed by the equivalent model. The results show that with the decrease of the breach area of the guard, the moment of PMT implosion caused by the collision of water flow is correspondingly advanced, the pulse width of the shock wave generated by the implosion remains basically unchanged, and the peak value of the shock wave is significantly reduced. This study is helpful for finding an effective PMT implosion protection method.
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Key words:
- implosion /
- shock wave /
- photomultiplier tube /
- implosion protection
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图 5 数值模拟与试验测点压力对比
Figure 5. Comparison of the simulation and test pressures of the measuring points
图 6 数值模拟与试验测得的比冲量对比
Figure 6. Comparison of the simulation and test impulse of the measuring points
图 13 A1测点冲击波压力变化
Figure 13. Shock wave pressures varied with time at measuring point A1
图 16 压力峰值与水流前锋速度变化
Figure 16. Variation of the peak pressure and the velocity of water front
表 1 数值模拟与试验所得的测点压力峰值对比
Table 1. Difference between the simulation and test peak pressures of the measuring points
测点 压力峰值/MPa 误差/% 测点 压力峰值/MPa 误差/% 试验 数值模拟 试验 数值模拟 1 14.13 12.87 8.9 3 7.08 6.65 6.1 2 7.68 6.65 13.4 4 3.19 2.85 10.7 
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表 2 数值模拟与试验所得的测点比冲量峰值对比
Table 2. Difference between the simulation and test peak impulse of the measuring points
测点 比冲量峰值/(kPa·s) 误差/% 测点 比冲量峰值/(kPa·s) 误差/% 试验 数值模拟 试验 数值模拟 1 1.58 1.35 14.6 3 0.87 0.83 4.6 2 1.21 0.91 24.8 4 0.32 0.28 12.5
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表 3 破碎面积具体值
Table 3. The value of break area
α Sb/m2 α Sb/m2 1.0 0.785 0.8 0.628 0.9 0.707 0.7 0.550
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