几种碳氢燃料与空气混合物相对爆轰敏感度的测定

利用矩形激波管测定了几种碳氢燃料（丁烷，石脑油，ＪＣ５，戊烯，已烯）直接起爆时形成爆轰所需的临界起爆能，并以化学当量比的乙炔氧气混合物直接起爆形成爆轰的临界起爆能为基准，定义了一个无量纲常数Ｄｈ。再利用这个常数，比较了这几种燃料的相对爆轰敏感度。     

丁烷与空气混合物的爆炸性能测定

在不同条件下,对丁烷与空气混合物进行爆炸实验,由微机数采测试系统测定其爆炸参数（爆轰波压力、爆轰波传播速度等）、爆轰极限以及当其形成爆轰时所需的临界起爆能。通过实验测定,为评价丁烷与空气混合物的安全性能提供重要依据     

Decomposing detonation and deflagration properties of ozone/oxygen mixtures

In this study, the decomposing detonation and deflagration properties of ozone/oxygen mixtures of up to 20 vol.% of ozone in oxygen under high pressure of up to 1.0 MPa in a tube were experimentally investigated. The mixtures were ignited by an electric spark at the end of the tube. Flame propagation properties such as flame velocity and pressure were measured with thermocouples and piezo electric transducers mounted along the tube. Slow and constant flame propagation profiles were obtained. We also investigated the quenching ability of a wire gauze as well as the concentration limit for flame propagation. However, in spite of slow flame propagation velocity and easy flame quenching properties under these experimental conditions, direct initiation of detonation by the driver detonation of the stoichiometric oxy-hydrogen mixture was easily achieved at much lower concentrations than the limit of deflagration. The observed detonation properties, such as wave velocity and pressure, agreed fairly well with C–J calculated values. The detonation velocity (900–1200 m/s) and the pressure ratio to initial pressures (5–9.5) were not affected by the initial pressure of the mixtures. Near the detonation limit, typical spinning detonations with oscillatory pressure waves were observed.     

氢气爆炸特性研究

本文研究、总结了氢气与空气(氢气与氧气)的混合物的爆炸特性.即氢气在空气中,在比较低燃烧界限的情况下,只有向上的传播和非常少的超压可以观测得到.正因为氢气的这种特性,将氢应用于科技将极大地推进社会进步,氢燃料将成为一种主要的能源.然而,氢技术应用的成功与否主要取决于氢使用的安全性.所以,必须掌握实际使用时氢气燃烧的性能.本文在日本过去十年实验数据的基础上,通过实验研究了氢气与空气混合物的燃点.研究了氢气、氧气混合物经氮气稀释后,按化学当量比例将不同浓度的氢气与空气进行混合,并得出了低温下的爆炸压力特性.随后,分别讨论了在初始压力下一致的情况下,试管直径相同的状况下,氢气与空气混合浓度相同的情况下,这三种爆轰传播限制之间的关系.得出了在空气中直接点燃的发生爆轰的最小试管直径,最小的装药量之间的关系,进行了爆轰危险性分级.最后,文章概括比较了氢与其他燃料的燃烧特性,评估了氢气燃烧过程中的危险与安全因素.     

Regimes and critical conditions of detonation propagation in expanding channels in gas suspensions of ultrafine aluminum particles

Under study are the regimes of detonation propagation in channels with linear expansion filled with monodisperse mixtures of oxygen and ultrafine aluminum particles of various loading; the methods of numerical simulations are used. The detonation combustion of submicron aluminum particles is described within the semi-empirical model of reduced kinetics with due regard to the transition from the diffusion-limited regime of combustion to the kinetic one. Waves of both planar and developed cellular detonation are considered as initial conditions. The characteristics of the main flow regimes are obtained and described: the subcritical (detonation failure), critical (detonation failure in some part of the channel) and supercritical (continuous detonation propagation). The maps of flow regimes in suspensions of 200-nm – 400-nm particles are presented in the plane of parameters: the channel width, expansion angle. The obtained critical conditions are similar to those observed in the gas detonation. The critical channel width linearly depends on the expansion angle up to a first critical value (35°–38°). Behind the second critical value (50°), the channel width is independent on the expansion angle. Between these values, there is an interval of nonmonotonicity similar to the detonation of micro-sized suspensions of aluminum particles. The effect of particle loading on the critical conditions in poor mixtures appears in the form of a sharp increase in the critical channel width, if the mass concentration falls below 0.25.     

Comments on explosion problems for hydrogen safety

The future widespread use of hydrogen as an energy carrier brings in safety issues that have to be addressed before public acceptance can be achieved. The prediction of the consequences of a major accident release of hydrogen into the atmosphere or the contamination of high-pressure hydrogen storage facilities by air entrainment requires a good knowledge of the explosion parameters of hydrogen–air mixtures. The present paper reviews and comments on the current knowledge of dynamic parameters of hydrogen detonation for hazard assessment. The major problem that remains to be resolved involves the understanding of the effect of turbulence on the cellular detonation structure, the propagation of high-speed deflagrations and the transition from deflagration to detonations. It is recommended that future research should be aimed towards experiments that permit the quantitative understanding of the mechanisms of high-speed turbulent combustion rather towards large-scale tests in complex geometries where minimal quantitative information of fundamental significance could be extracted. In spite of its wide flammability and sensitivity to ignition and detonation initiation, it is felt that hydrogen can be produced, stored and handled safely with the appropriate considerations in the design of the hydrogen facilities.     

Minimum propagation diameter and thickness of high explosives

The critical diameter and critical thickness of two heterogeneous explosives were measured experimentally. By comparing these experimentally determined values of critical diameter and critical thickness, the role of front curvature in the failure of the detonation can be investigated. Current theories of detonation based on front curvature would predict the critical diameter should be twice the critical thickness. Experimentally, the expected two-to-one ratio was only validated for the case of a heterogeneous explosive with very fine scale heterogeneities. The ratios of critical diameter to critical thickness (for the two selected explosives) are also compared to previously measured values for homogeneous (liquid) explosives in order to contrast the dominant failure mechanism in these different explosives.     

非均质炸药冲击起爆临界判据中起爆参数的研究

以引信传爆序列中传爆管——主装药界面间的爆轰传递为例,研究了非均值炸药的冲击起爆理论,推导了飞片起爆和透射冲击起爆过程中爆轰界面的关键参数ｐ 和τ的计算关系式,对临界起爆能量的计算以及传爆序列的安全设计具有一定的指导意义。     

Analysis of the experimental results of the initiation of detonation in short tubes with kerosene–oxidizer mixtures

The paper describes the experimental investigation of detonation initiation in a mixture of kerosene–oxidant in a short test tube. Various mixtures of oxygen and nitrogen were used as an oxidant, from pure oxygen to the composition of air. The goal of the study was to determine the minimum diameter of the tube and the minimum level of energy needed for the direct initiation of detonation. As a result of the measurements the pressure courses were obtained for two kinds of cases: with and without (only shock waves) of fuel injection. The results of both kinds of measurements were compared, providing information about the initiation of detonation in a fuel–oxidizer mixture. Brief analyses of the results for different initiators and different oxidizers were performed and compared with the shock wave and Chapman–Jouget velocity.     

Reactive shock and detonation propagation in U-bend tubes

The objective of the research outlined in this paper was to provide new experimental and computational data on initiation, propagation, and stability of gaseous stoichiometric propane–air detonations in tubes with U-bends. Extensive experimental and computational studies with the tube 51 mm in diameter with U-bends of two curvatures and two different shock-wave generators were performed. Numerical simulations of the process were used to reveal the salient features of the accompanying phenomena.     

Methane–air detonation experiments at NIOSH Lake Lynn Laboratory

The methane–air detonation experiments are performed to characterize high pressure explosion processes that may occur in sealed areas of underground coal mines. The detonation tube used for these studies is 73 m long, 105 cm internal diameter, and closed at one end. The test gas is 97.5% methane with about 1.5% ethane, and the methane–air test mixtures varied between 4% and 19% methane by volume. Detonations were successfully initiated for mixtures containing between 5.3% and 15.5% methane. The detonations propagated with an average velocity between 1512 and 1863 m/s. Average overpressures recorded behind the first shock pressure peak varied between 1.2 and 1.7 MPa. The measured detonation velocities and pressures are close to their corresponding theoretical Chapman-Jouguet (CJ) detonation velocity (D_CJ) and detonation pressure (P_CJ). Outside of these detonability limits, failed detonations produced decaying detached shocks and flames propagating with velocities of approximately 1/2 D_CJ. Cell patterns on smokefoils during detonations were very irregular and showed secondary cell structures inside primary cells. The measured width of primary cells varied between 20 cm near the stoichiometry and 105 cm (tube diameter) near the limits. The largest detonation cell (105 cm wide and 170 cm long) was recorded for the mixture containing 15.3% methane.     

石化行业中某些碳氢燃料爆炸危险性分析

借助于激波管测定了几种碳氢燃料和空气混合物的爆轰极限、临界起爆能。根据这些实验数据，分析了所研究的碳氢燃料的爆炸危险性。同时根据烷烃和烯烃键的不同饱和度，分析了它们爆炸危险性差别的原因。     

Initiation of strong reactive shocks and detonation by traveling ignition pulses

Experimental studies of detonation initiation by external stimulation of exothermic reactions closely behind a propagating shock wave (SW) are reported. Gaseous and heterogeneous fuel–air mixtures have been studied. Spatially distributed electric dischargers with properly tuned triggering times are shown to provide very short distances for shock-to-detonation transition in smooth-walled tubes. The energy of each individual discharger was shown to be smaller than the critical energy required for direct detonation initiation by a single discharger. The total energy of the dischargers appeared to be lower than the critical energy of direct detonation initiation. Available experiments with deflagration-to-detonation transition (DDT) in tubes with regular or irregular obstacles are also treated as detonation initiation by a traveling ignition source. In this case, instead of external stimulation of chemical activity, the localized obstacle-induced autoignition of shock-compressed gas occurs which can be closely coupled with the propagating SW. Two possible DDT scenarios are identified, namely, ‘fast’ and ‘slow’ DDT. In case the ignition timing at obstacles is closely coupled with the SW, favorable conditions for ‘fast’ DDT can occur. Otherwise, the SW decouples from the ignition pulses and ‘slow’ DDT can occur at a later stage due to cumulating of flame-induced pressure waves and ‘explosion in the explosion’ phenomenon.     

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.     

工业粉尘“二次爆炸”过程研究

开展了工业粉尘“二次爆炸”过程实验室研究工作。对玉米淀粉、小麦粉等粮食粉尘进行了研究，得到了“二次爆炸”发展过程以及最后形成的爆轰波特性，还进一步研究了粉尘层冲击波卷扬过程和分析讨论了粉尘“二次爆炸”过程的影响因素。     

Influence of non-reactive particle cloud on heterogeneous detonation propagation

An interaction of a detonation wave propagating in the cellular detonation mode with a cloud of inert particles is investigated numerically. The analysis of results allows the regimes of propagation of the heterogeneous plane Chapman–Jouguet and cellular detonations and their suppression to be identified. The influence of various parameters of the inert cloud is demonstrated. The critical length of the cloud sufficient for detonation suppression is determined. It is shown that the disperse composition and the nonuniform distribution of particles in the cloud are important parameters affecting the detonation propagation mode.     

Estimation of the liability to detonating of prilled ammonium nitrate fertiliser grade

The statistical analysis of the results of testing liability to detonation of coated and uncoated prilled ammonium nitrate was performed. The correlation between the crushing of the lead cylinders as a result of the so-called 4″ tube test and the chemical as well as the physical properties of ammonium nitrate were determined. The results demonstrated that the liability to detonation of ammonium nitrate may be estimated by use of mathematical equations, which employ easily obtainable experimental values relating to the chemical composition and physical properties of the tested fertilisers.     

Comparison of explosion models for detonation onset estimation in large-scale unconfined vapor clouds

Although industrial denotations in semi-open and congested geometries are often neglected by many practitioners during risk assessment, recent studies have shown that industrial detonations might be more common than previously believed. Therefore, from the explosion safety perspective, it becomes imperative to better assess industrial detonation hazards to improve robustness of explosion mitigation design, emergency response procedures, and building siting evaluation. Having that in mind, this study aims to review current empirical vapor cloud explosion models, understand their limitations, and assess their capability to indicate detonation onset for elongated vapor clouds. Six models were evaluated in total: TNO Multi-Energy, Baker-Strehlow-Tang (BST), Congestion Assessment Method (CAM), Quest Model for Estimation of Flame Speed (QMEFS), Primary Explosion Site (PES), and Confinement Specific Correlation (CSC). Model estimations were compared with large-scale test data available in the open literature. The CAM model demonstrated good performance in indicating deflagration-to-detonation transition (DDT) for test conditions experiencing detonation onset without any modification in the methodology. Some suggestions are provided to improve simulation results from PES, BST and QMEFS.     

Numerical simulation of propane detonation in medium and large scale geometries

A modelling strategy has been developed for consequence analysis of medium and large scale gaseous detonation. The model is based on the solution of Euler equations with one-step chemistry. The Van Leer flux limited method which is a total variation diminishing scheme is used for shock capturing. Preliminary calculations were firstly conducted for small domains with fine grids which resolve the wave, relatively coarse grids which have less than 10 grids across the wave and coarse grids in which the minimum grid size is larger than the wave thickness to ensure that the reaction scheme has been properly tuned to capture the correct detonation pressure, temperature and velocity in the resolutions used in the different cases. The model was firstly tested against a medium scale detonation test in a shock tube with U-bends. Reasonably good agreement is achieved on detonation pressure and mean shock wave velocities at different measuring segments of the tube. Following the validation, the detonation of a hypothetical planar propane-air cloud is simulated. The predictions uncovered some interesting features of such large scale detonation phenomena which are of significance in the safety context, especially for accidental investigations. The findings from the present analysis are in line with the forensic evidence on damages in some historic accidents and challenges previous analysis of a major accident in which forensic evidence suggested localised detonation but was considered as the consequence of fire storms by the investigation team.