输气管道高后果区蒸气云爆炸超压预测方法探究

为准确预测输气管道高后果区在发生蒸气云爆炸事故时的超压分布情况,对国内外运用较为广泛的蒸气云爆炸超压预测经验模型和数值模拟方法进行调研,并分别应用其对某输气管道全尺寸泄漏燃爆实验进行超压预测,结合实验数据和输气管道高后果区管理现状进行方法准确性和工程适用性分析。研究结果表明：基于等效TNT假设的Henrych模型、Mills模型和等效TNT当量数值模拟方法均不适合准确预测蒸气云爆炸超压,TNO多能法和混合气体数值模拟方法所预测的结果较为接近实验结果。TNO多能法使用简便且推广性强,但主观性较大,易高估或低估爆炸后果;混合气体数值模拟方法操作繁琐且推广性差,但分析结果精度较高。在对高后果区进行安全管控时,可结合TNO多能法与混合气体数值模拟方法同时对管道工况进行评估,确定TNO多能法的爆源强度等级,继而推广使用TNO多能法。该研究结果可在较大程度上保证评估的准确性并节约成本。     

蒸气云爆炸荷载计算方法比选研究

通过比较计算爆炸荷载的4种常用方法：三硝基甲苯(Trinitrotoluene, TNT)当量法、贝克-斯特洛-唐(Baker-Strehlow-Tang, BST)法、荷兰应用科学研究组织(Netherlands Organization for Applied Scientific Research, TNO)多能法和计算流体动力学(Computational Fluid Dynamics, CFD)方法，得出对于石油化工行业易发的蒸气云爆炸，推荐采用TNO多能法或CFD方法的结论。通过构建蒸气云爆炸场景，定量评估TNO多能法或CFD方法在单爆炸场景计算中的准确度和适用性。研究结果显示，在爆炸冲击波近场，CFD方法在计算中考虑了障碍物对爆炸冲击波的遮挡效应，其近场的计算结果更为可信，但是在爆炸冲击波远场通常会高估爆炸冲击波衰减速度。TNO多能法在爆炸冲击波远场的计算中更有优势，但在爆炸冲击波近场的计算结果受使用者主观影响较大。研究成果可为学者科学地选择计算方法，并准确评估爆炸荷载提供参考和依据。     

基于超压值地铁上覆管道爆炸对隧道及人员安全影响研究*

为分析地铁上覆管道爆炸对乘客安全影响,采用基于超压冲击波阀值数值模拟,通过将泄漏气体能量等效为TNT当量,分析不同泄漏模式爆炸冲击波对地铁隧道及人员安全影响。结果表明:爆炸产生的超压冲击波对隧道及人员影响小于限值,不会造成人员伤亡,研究结果可为地下工程下穿油气管线安全影响分析提供理论支撑。     

蒸气云爆炸模型在原油储罐火灾事故中的应用研究

本文分析了原油储罐的火灾爆炸事故特点,介绍了蒸气云爆炸模型中热辐射伤害模型以及TNT模型和TNO模型。选取蒸气云爆炸TNT模型以及热辐射伤害模型对10×104m3原油储罐泄漏事故形成的蒸气云爆炸进行后果定量分析,对事故产生的热辐射和冲击波对人员造成的伤害程度进行了对比分析,得出目标到爆炸源距离较近时热辐射对人员造成的伤害较大,目标到爆炸源距离较远时冲击波对人员造成的伤害较大。     

蒸气云爆炸后果预测模型的比较研究

介绍了3种蒸气云爆炸后果预测模型,分别是TNT当量模型、多能法、Baker-Strehlow模型。阐述了这些模型的基本原理,将3种模型进行了对比研究,并将3种模型的无量纲距离和超压关系绘制在了同一图中。对某一蒸气云的爆炸后果进行了预测,并对结果进行了分析,指出了不同模型的优缺点。     

固体推进剂危险性分级方法的探讨

探讨用50％爆轰的卡片隔板值24.1mm和TNT当量值1为标准,以区加紧推进剂的危险级别为爆炸级或燃烧级。本文主要从美国所发表的各种火药TNT当量试验结果资料中,推测用TNT当量值区别火药的燃烧和爆炸级,并应用于推进剂分级,再从我国对各种炸药的隔板值选择铸装TNT的隔板值作为区分推进剂的燃烧级和爆炸级。     

固体推进剂危险性分级方法的探讨

探讨用50％爆轰的卡片隔板值24．1mm和TNT当量值1为标准，以区加紧推进剂的危险级别为爆炸级或燃烧级。本主要从美国所发表的各种火药TNT当量试验结果资料中，推测用TNT当量值区别火药的燃烧和爆炸级，并应用于推进剂分级，再从我国对各种炸药的隔板值选择铸装TNT的隔板值作为区分推进剂的燃烧级和爆炸级。     

城市危险源爆炸灾害应急损失评估研究

采用冲击波伤害-破坏超压准则,首先确定了不同当量TNT炸药爆炸引起的人员伤害区域和建筑物破坏区域;再通过确定危险物爆炸所产生热量值的大小,将各种危险物料转化为相应当量的TNT炸药,可用于评估各种不同危险物料爆炸所造成的损失。同时,结合GIS软件平台,编制了爆炸灾害评估模拟程序。在软件平台中以图形的形式给出了设定条件下人员伤害区域及建筑物破坏区域的范围,根据区域内的人员分布和建筑物造价、财产多少,给出了定量的人员伤亡和经济损失应急评估。     

汽车爆炸的超压分布规律实验研究

测试了不同药量和不同车型的爆炸超压值,对汽车爆炸的超压分布规律进行了实验研究.结果表明,小汽车内发生炸药爆炸时,车门侧压力明显大于车尾部方向的压力,车外的冲击波超压值要大于空气中炸药爆炸的结果,前者约为后者的1.0～2.2倍.即车体对冲击波约束作用要小于车内底盘的反射作用.计算得到了实验中冲击波超压对人员的杀伤半径和最小安全距离,对汽车爆炸案件具有一定指导作用.冲击波的反射不可忽视,货车下地面炸药爆炸表现出明显的冲击波反射作用,测得超压值大于空气中爆炸的超压值.     

苯的蒸气云爆炸伤害分析

介绍了蒸气云爆炸事故机理以及4种方法研究蒸气云爆炸破坏力的影响范围,并根据TNT当量法和TNO建议,计算苯蒸气云燃烧爆炸冲击波的影响范围,即确定死亡半径、重伤半径、轻伤半径及财产损失半径,为企业和政府的应急救援提供帮助。     

A quantitative correlation of evaluating the flame speed for the BST method in vapor cloud explosions

In recent decades, vapor cloud explosions (VCEs) have occurred frequently and resulted in numerous personnel injuries and large property losses. As a main concern in the petrochemical industry, it is of great importance to assess the consequence of VCEs. Currently, the TNT equivalency method (TNT EM), the TNO multi-energy method (TNO MEM), and the Baker-Strehlow-Tang (BST) method are widely used to estimate the blast load from VCEs. The TNO MEM and BST method determine the blast load from blast curves based on the class number and the flame speed, respectively. To quantitatively evaluate the flame speed for the BST method, the experimental data is adopted to validate the confinement specific correlation (CSC) for the determination of the class number in the TNO MEM. As a bridge, a quantitative evaluation correlation (QEC) between CSC correlation and the flame speed is established and the blast wave shapes corresponding to different flame speeds are proposed. CFD software FLACS was used to verify the quantitative correlation with the numerical models of three geometrical scales. It is found that the calculated flame speeds by the QEC are in good agreement with the simulated ones. A petrochemical plant is selected as a realistic scenario to analyze the TNT EM, TNO MEM, BST method and FLACS simulations in terms of the positive-phase side-on overpressure and impulse at different distances. Compared with the flame speed table, the predicted overpressure from BST curves determined by the proposed QEC is closer to that from FLACS and more conservative. Furthermore, the predicted results of different methods are compared with each other. It is found that the estimated positive-phase side-on overpressure and impulse by the TNO MEM are the largest, and the estimated impulse by the TNT EM is the smallest. Moreover, the estimated overpressure and impulse are larger in the higher reactivity gas.     

Measurement of gas detonation blast loads in semiconfined geometry

The ignition and explosion of combustible vapor clouds represents a significant hazard across a range of industries. In this work, a new set of gas detonations experiments were performed to provide benchmark blast loading data for non-trivial geometry and explosion cases. The experiments were designed to represent two different accident scenarios: one where ignition of the vapor cloud occurs shortly after release and another where ignition is delayed and a fuel concentration gradient is allowed to develop. The experiments focused on hydrogen-air and methane-oxygen detonations in a semiconfined enclosure with TNT equivalencies ranging from 9 g to 1.81 kg. High-rate pressure transducers were used to record the blast loads imparted on the interior walls of a 1.8 m × 1.8 m × 1.8 m test fixture. Measurements included detonation wave velocity, peak overpressure, impulse, and positive phase duration. A comparison of the pressure and impulse measurements with several VCE models is provided. Results show that even for the most simplified experimental configuration, the simplified VCE models fail to provide predictions of the blast loading on the internal walls of the test fixture. It is shown that the confinement geometry of the experiment resulted in multiple blast wave reflections during the initial positive phase duration portion of the blast loading, and thus, significantly larger blast impulse values were measured than those predicted by analytical models. For the pressure sensors that experienced normally-reflect blast waves for the initial blast impulse, the Baker-Strehlow and TNT equivalency models still struggled to accurately capture the peak overpressure and reflected impulse. The TNO multi-energy model, however, performed better for the case of simple normally-reflected blast waves. The results presented here may be used as validation data for future model or simulation development.     

Experimental study on unconfined methane explosion: Explosion characteristics and overpressure prediction method

Explosion accidents have become the main threat for the high-efficiency use of cleaner gas energy sources, such as natural gas. During an explosion, obstacle causing flame acceleration is the main reason for the increase of the explosion overpressure, which still remains to be fully understood. In this research, field experiments were conducted in a 1 m³ cubic frame apparatus to investigate the effect of built-in obstacles on unconfined methane explosion. Cage-like obstacles were constructed using square steel rods with different cross section size. The results demonstrated that the flame could get accelerated due to the hydrodynamic instability and obstacle-induced turbulence, which enhanced the explosion overpressure. In the near field, the overpressure wave travelled slower and the maximum overpressure could almost keep constant. Reducing the cross section size, or increasing the obstacle height or the obstacle number per layer could determine the rise of the maximum overpressure, the maximum pressure rising rate and the overpressure impulse. For uniformly constructed obstacles, self-similar theory was chosen to measure the influence of the hydrodynamic instability, and a parameter β was adopted to measure the flame acceleration caused by obstacle-induced turbulence, the value of which was 2 in this research. Based on the acoustic theory, an overpressure prediction model was proposed and the predicted results agreed with the measured values better than previous models, such as TNT equivalency model and TNO multi-energy model.     

Characteristic overpressure–impulse–distance curves for the detonation of explosives, pyrotechnics or unstable substances

A number of models have been proposed to calculate overpressure and impulse from accidental industrial explosions. When the blast is produced by explosives, pyrotechnics or unstable substances, the TNT equivalent model is widely used. From the curves given by this model, data are fitted to obtain equations showing the relationship between overpressure, impulse and distance. These equations, referred to here as characteristic curves, can be fitted by means of power equations, which depend on the TNT equivalent mass. Characteristic curves allow determination of overpressure and impulse at each distance.     

石化行业控制室承爆风险评估方法研究

针对传统的气体爆炸风险评估方法的不足之处,提出采用一种基于CFD技术的气体爆炸风险评估方法,对某煤气化厂区氢气爆炸对控制室造成的风险进行模拟计算与预测分析。并把研究结果与传统的TNT当量法、Multi-Energy方法预测结果进行比较。结果表明,该方法能考虑到密集管道与复杂装置布局、气云大小等因素对爆炸超压的影响,且能用于超压波的近场预测,以及确定空间不同位置处的爆炸超压,更适用于石化行业控制室的承爆风险评估。     

Propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation

The coupled fluid-structure-rupture model was developed to study the propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation. The dynamic rupture of pipe and propagation of blast wave were well coupled together in every timestep during the simulation. The numerical model was validated with experiments in terms of both typical rupture profiles and blast overpressures. Results reveal that crack branching of pipe can dramatically increase the rupture opening rate which controls the intensity and shape of the resultant blast wave. Due to the process of crack initiation and extension, the blast wave out of the pipe first forms and then is strengthened by the subsequent compression waves. This makes the maximum peak overpressure appears at a certain standoff distance above the rupture. Despite consuming some percentages of energy, the dynamic rupture of pipe generally presents positive effects (up to 2–3 times) on the blast wave intensity along the jetting direction due to the convergence effect of rupture opening on the release of internal high-pressure gas. Finally, through defining normalized overpressure and impulse based on the same hydrogen detonation in open spaces, the quantitative influences of pipe rupture on the blast wave intensity in cases of different detonation pressures and standoff distances are clarified.     

Numerical simulation of far-field blast loads arising from large TNT equivalent explosives

Large TNT equivalent explosions usually arise from accidents occurring during the transportation, storage, and manufacturing of chemicals relevant to process industries. The blast wave generated by the explosion will spread and interact with the surrounding factories and storehouses, damaging the building structures within several kilometers and causing significant casualties and property losses. This study aims to develop an efficient numerical simulation method to predict blast loads to estimate the consequences of accidents involving far-field free air bursts or surface burst explosions. Before its interaction with the interested target, a blast wave is generated in the numerical model by specifying the initial and boundary conditions of the disturbed air. Based on empirical data of incident overpressure, an explicit formula to calculate the air particle velocity is derived from the governing equations of a perfect inviscid gas. A simplified path line method is proposed to calculate the air density. The proposed method is applied to the LS-DYNA CESE solver to simulate the blast loads on building structures in the far field. Validations against empirical data and experiments indicate that the proposed method is sufficiently accurate for engineering applications and, through a case study, presents a more efficient performance than the LOAD_BLAST_ENHANCED (LBE) and mapping methods.     

燃料空气炸药一次引爆爆炸效应实验研究

为了提高燃料空气炸药（FAE）爆炸威力,设计制备了不同相态的FAE,并采用光测和电测方法,开展了开放空间下FAE一次引爆对比实验研究。结果表明:固态、液固混合及液态FAE被一次引爆后,均存在引爆中心装药、抛撒燃料、点火和爆炸4个阶段,云雾存续时间均长于等质量TNT装药的相应值,随着距离增加,固态FAE爆炸场超压变化规律为“减少-增加-减少”,其值高于等质量TNT装药的相应值;液态、液固混合FAE爆炸场超压变化规律为“增加-减少”,远场超压高于等质量TNT装药的相应值。