Effects of a T-shaped branch pipe on overpressureof gasoline-air mixture explosion
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摘要: 为了研究T型分支结构对管道内油气爆炸压力的影响，进行了不同初始油气体积分数、不同初始点火能工况下多参数对比实验，并对火焰传播进行了可视化研究。实验结果表明：T型分支管道对油气爆炸压力有强化作用，强化程度和初始油气体积分数关系密切，在当量比附近，强化程度表现最显著；初始点火能对油气爆炸最大超压影响显著，随着点火能的增大，最大爆炸超压呈线性增长；波的绕射和反射、流场湍流度增强、管道通道面积增大和障碍物扰动是导致T型分支管道内爆炸压力增强的主要因素；T型分支管道会导致火焰阵面严重地弯曲褶皱变形，增大火焰面积，并且回传火焰对T型分支结构壁面具有较强的破坏作用。Abstract: To investigate the effects of a T-shaped branch structure on the overpressures during the explosions of the gasoline-air mixture in a pipe, we conducted multiple parameter contrast experiments under the conditions of different initial gasoline vaper volume fractions and different initial ignition energy, and carried out visualized investigation on the flame propagation of the mixture. Our research reveal the following results: the T-shaped branch pipe can enhance the explosive overpressure of the gasoline-air mixture in a pipe, and the degree of this enhancement is closely related with the increase of the initial gasoline vaper volume fraction approximately in a parabolic trend, and with the maximum value obtained around the stoichiometric initial concentration. The maximum explosive overpressures before and after the T-shaped branch pipe increases linearly with the growth of the initial ignition energy. The effects of the T-shaped branch pipe on raising the degree of the explosion mainly originate from four factors: the wave diffraction and reflection, the turbulence enhancement, the sudden expansion of the pipe cross-section area and the reinforcement of the disturbance by the obstacles. It can be seen from the visual analysis that, when the flame propagates through the T-shaped branch pipe, the flame front is distorted seriously into creases, the flame surface area is enlarged, and the returning flames are observed, which exerts a destructive effect on the wall of the T-shaped branch pipe.
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Key words:
- T-shaped branch pipe /
- gasoline-air mixture /
- explosion wave /
- visualization
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图 3 不同初始点火能下油气起爆过程
Figure 3. Initial explosion progress of gasoline vaper at different initial igintion energies
图 5 两对比实验中爆炸超压随时间和空间的变化
Figure 5. Explosion overpressure varying with time and space in two contrast experiments
图 6 两对比实验测点1、2最大爆炸压力随初始油气体积分数的变化
Figure 6. Maximum explosion pressure of measuring points 1 and 2 within two contrast experiments at different initial gasoline vaper volume fractions
图 7 不同初始油气体积分数下的压力强化因数
Figure 7. Enhancement coefficient of pressureat different initial gasoline vaper volume fractions
图 8 3种不同初始油气体积分数条件下测点1、2压力峰值随初始点火能变化关系
Figure 8. Peak overpressure of two measuring points varying with initial ignition energy at three different initial gasoline vaper volume fractions
图 9 火焰传播经过T型分支管道时的形态变化过程
Figure 9. Morphological changes of flame when propagating through T-shaped branch pipe
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