狭长受限空间液化石油气爆炸安全泄放动力学机理研究

LPG explosion hazards in narrow confined space could be effectively reduced by safety venting. However, the safety venting design of LPG explosion in narrow confined space would result in huge errors based on the current safety venting standards. Fully understanding the dynamic couplings of flame acceleration and explosion pressure during LPG explosion in narrow confined space is the basis of setting safety venting location, area, numbers and static action pressure. This project aims to obtain the critical conditions of flame acceleration during LPG explosion in narrow confined space by experimentally varying the equivalence ratio and concentration gradient of LPG-air mixtures, length-diameter ratios and obstacles of narrow confined space. Combined the heat and mass transfer and explosion reaction kinetics theory, the pressure prediction model coupled flame acceleration would be developed to evaluate the temporal and spatial distributions of pressure in narrow confined space. The dynamic couplings of vented flame and vented pressure during LPG explosion in narrow confined space and external domain would be revealed by experimentally varying the safety venting location, area, numbers and static action pressure. Based on the above experimental results and theory analysis, the safety venting model would be developed for LPG explosion in narrow confined space. The results would provide theoretical and technical support for prevention and mitigation of LPG explosions.

安全泄放技术可有效降低狭长受限空间液化石油气爆炸造成的危害，但依据现有泄放标准进行安全泄放设计会造成较大误差。只有充分地认识狭长受限空间液化石油气爆炸火焰加速传播与爆炸超压耦合动力学影响规律，才能科学合理地设置泄放口位置、面积、数量及静态开启压力，进而降低狭长受限空间液化石油气爆炸危害，保证液化石油气安全应用。本项目通过实验改变燃料当量比、浓度梯度、受限空间长径比及设置障碍物，获得狭长受限空间液化石油气爆炸火焰加速传播的临界条件，结合传热传质、爆炸反应动力学理论分析，建立耦合火焰加速传播的狭长受限空间液化石油气爆炸压力预测模型；依据狭长受限空间压力时空分布，通过改变泄放口位置、面积、数量及静态开启压力，获取狭长受限空间内部及泄放区域泄放火焰与泄放压力的耦合影响规律，基于上述实验结果建立狭长受限空间液化石油气爆炸安全泄放模型，研究成果可为防控液化石油气爆炸提供理论支持和技术支撑。

本项目搭建了狭长受限空间液化石油气爆炸安全泄放试验平台，利用高速摄像技术和高频动态压力测量技术，研究了当量比和长径比对狭长受限空间液化石油气爆炸火焰传播速度和爆炸超压的影响规律，揭示了狭长受限空间液化石油气爆炸火焰加速传播机理；研究了当量比、长径比、泄爆口直径、泄爆位置和静态动作压力对液化石油气爆炸内部/外部火焰形态演变和内部/外部爆炸超压的影响规律，揭示了泄放火焰与泄放压力的耦合作用机制，发展了考虑泄爆位置和泄爆面积的狭长受限空间液化石油气爆炸泄放超压预测泄放设计方法。结果表明：狭长受限空间液化石油气爆炸火焰形态难以维持平面火焰结构，致使试验工况下火焰前锋速度明显高于层流工况；随着当量比的增加，最大升压速率逐渐增加，爆炸超压峰值先增加后减小，最大值对应当量比是φ=1.2；随着长径比由L/D=3增至L/D=7，泄爆超压峰值逐渐减小（最大降幅148kPa），最大升压速率逐渐增加（最大增幅42.8MPa/s）。增加泄爆口直径可大幅度降低泄爆超压峰值（最大降幅408kPa），过大的泄爆口直径将强化诱导泄爆湍流，进而增强耦合声压；随着泄爆位置远离点火点，泄爆超压峰值先增加后减小，尾部泄爆效果最佳。考虑泄爆位置和泄爆面积的安全泄放设计方法可准确预测狭长受限空间液化石油气最大泄爆超压峰值，与NFPA68预测模型相比最大相对误差降低了90%。研究成果可为防控液化石油气爆炸提供理论支持和技术支撑。