Explosion characteristics of combustible wood dust in confined system: Analysis using oxygen consumption energy

Yun Seok Kim,이민철,이동호 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12

The explosion characteristics, such as maximum explosion pressure, rate of explosion pressure rise, explosion efficiency, were investigated to determine the roll and significance of oxygen consumption energy in dust explosion. Dust explosion experiments were conducted in a Siwek 20L spherical explosion apparatus for three wood dust samples from a wood-based panel production factory. Unlike gas explosions having maximum explosion pressure at near chemical stoichiometric concentration, both the maximum explosion pressure and the maximum rate of explosion pressure of wood dusts appeared at three times or much higher equivalence ratio. Although there were differences in particle size among tested dusts, in the case of dust of which the mean particle size was not larger than 100 ㎛, P maxappeared at lower equivalent ratios when mean particle sizes were smaller and at higher equivalent ratios when mean particle sizes were relatively larger. Explosion efficiency for all dusts are around 10 %, of which the value is relatively lower than most of other normal combustion, which signifies dust explosion remains 90 % of unburned dust with high fire risks after explosion. In a dust explosion, it is difficult to estimate the weight of suspended dust participating in explosions, especially in fuel rich conditions, so a method for estimating explosion overpressure by applying oxygen consumption energy based on unit volume (1 m 3 , SAPT condition) was newly proposed and verified from the result of explosion efficiency. To practically apply these results to dust treating industry, the assessment procedure for dust explosion influence has been provided by introducing TNT equivalent model and its scaled distance.

유체 동역학 코드를 이용한 화약의 폭발과정에 대한 수치 모델링

박도현 ( Do Hyun Park ),최병희 ( Byung Hee Choi ) 대한화약발파공학회 2016 화약발파 Vol.34 No.2

유체 동역학 코드는 고속 충돌을 모델링하는 수치해석 툴로서 재료가 유체처럼 거동한다고 가정하며, 화약을 이용한 암반발파와 같은 충돌 문제를 푸는 데 광범위하게 사용된다. 암반발파를 현실적으로 모사하기 위해서는 화약을 수치해석적으로 모델링할 필요가 있으며, 이를 통해 암반과 화약의 상호작용 문제를 완전 연계된 방식으로 풀 수 있다. 화약을 수치 모델링하기 위해서는 특정 물리적 조건에서 재료의 상태를 나타내는 상태방정식이 수립되어야 한다. 본 고에서는 발파 과정을 수치 모델링하기 위한 유체 동역학 코드, 화약의 상태방정식과 관련 매개변수의 결정방법에 대해 소개하였다. The hydrodynamics code is a numerical tool developed for modeling high velocity impacts where the materials are assumed to behave like fluids. The hydrodynamics code is widely used for solving impact problems, such as rock blasting using explosives. For a realistic simulation of rock blasting, it is necessary to model explosives numerically so that the interaction problem between rock and explosives can be solved in a fully coupled manner. The equation of state of explosives, which describes the state of the material under given physical conditions, should be established. In this paper, we introduced the hydrodynamics code used for explosion process modeling, the equation of state of explosives, and the determination of associated parameters.

Boundary conditions and experimental observation of micro-explosion for water-ethanol diesel emulsified fuel droplets

( Xiaoqing Zhang ),( Tie Li ),( Jianpeng Song ),( Bin Wang ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

Droplet micro-explosion is a severe crushing phenomenon of emulsified fuel droplets during heating and evaporation. It is caused by overheating and vaporization of light components as the temperature rising to the extreme heat. Currently there are mainly two methods for solving the limit of superheat: Avedisian-Glassman kernel method and the intermolecular potential model. For the former, the nucleation rate obtained by this method is much smaller than the experimental observation, and also the surface tension for the activation energy of the molecule is not suitable for micro-size. While for the latter, it can only apply to pure liquid. Based on the Avedisian-Glassman kernel method and the intermolecular potential model, a solution for the three-component droplet micro-explosion limit of aqueous ethanol diesel emulsified fuels. Considering that the water and ethanol between the main bond energy is larger than other potential hydrogen bonding by one to two orders of magnitude, recombining the number density of molecules and the structure of molecular clusters, the hydrogen bond saturation is revised, further the activation energy of molecules can be calculated, the temperature boundary conditions for micro-explosion of water-ethanol diesel emulsified fuel droplets are obtained last. This method is not only applicable for pure liquids such as water and alcohols, but also for fuels with small liquid molecules and intermolecular potential energy with hydrogen bonds. The result of the superheat limit temperature of water under atmospheric pressure by using this method is consistent with the value of present literatures well. For more, the micro-explosion temperature boundary conditions for a kind of aqueous ethanol diesel emulsified fuel(HE30) droplet is calculated by using this method, and an observation experiment for micro-explosion is conducted to verify calculation results at last.

Nonlinear numerical modelling for the effects of surface explosions on buried reinforced concrete structures

Nagy, N.,Mohamed, M.,Boot, J.C. Techno-Press 2010 Geomechanics & engineering Vol.2 No.1

The analysis of structure response and design of buried structures subjected to dynamic destructive loads have been receiving increasing interest due to recent severe damage caused by strong earthquakes and terrorist attacks. For a comprehensive design of buried structures subjected to blast loads to be conducted, the whole system behaviour including simulation of the explosion, propagation of shock waves through the soil medium, the interaction of the soil with the buried structure and the structure response needs to be simulated in a single model. Such a model will enable more realistic simulation of the fundamental physical behaviour. This paper presents a complete model simulating the whole system using the finite element package ABAQUS/Explicit. The Arbitrary Lagrange Euler Coupling formulation is used to model the explosive charge and the soil region near the explosion to eliminate the distortion of the mesh under high deformation, while the conventional finite element method is used to model the rest of the system. The elasto-plastic Drucker-Prager Cap model is used to model the soil behaviour. The explosion process is simulated using the Jones-Wilkens-Lee equation of state. The Concrete Damage Plasticity model is used to simulate the behaviour of concrete with the reinforcement considered as an elasto-plastic material. The contact interface between soil and structure is simulated using the general Mohr-Coulomb friction concept, which allows for sliding, separation and rebound between the buried structure surface and the surrounding soil. The behaviour of the whole system is evaluated using a numerical example which shows that the proposed model is capable of producing a realistic simulation of the physical system behaviour in a smooth numerical process.

CO2 임시 저장 탱크에서의 물리적 폭발에 따른 피해영향 고찰

서두현,장갑만,이진한,이광원 한국가스학회 2015 한국가스학회지 Vol.19 No.2

CCS(Carbon Dioxide Capture and Storage)은 온실가스의 주원인 중 하나인 CO2를 감축하기 위한 대안으로 발전, 시멘트 및 철강 산업 등에서 발생하는 대량의 CO2를 포집, 압축․액화하여 저장소에 격리하는 일련의 전 과정을 말한다. 이때, 포집된 CO2는 수송 과정 전․후에 임시저장소에 저장 하게 된다. CO2는 일반적으로 비 가연성, 무독성가스로 저장소에서 화학적 폭발을 일으킬 가능성이 희박한 가스지만, 임시로 저장되어 보관될 동안 100bar이상의 압력으로 보관되고 있으며, 포집된 가스에 포함된 불순물과 산화물 등에 의해 용기의 부식으로 인한 물리적 폭발이 일어날 가능성이 있다. 폭발 강도는 일반적으로 TNT 상당질량을 통해 계산할 수 있으며, CO2 임시 저장소는 대량의 CO2를 보관하기위한 시설로 용기의 용량을 100,000L(100톤)로 가정하여 계산하였다. 계산을 통하여 약 100bar로 압축되어 저장된 100톤의 임시저장소 1개가 폭발할 때의 폭발위력을 산출하면, 대략 2346 lb 이며, 이를 환산하면 약 1064 kg의TNT가 폭발하는 위력과 동일한 것으로 계산된다. 폭발중심으로부터의 거리에 따른 과압은 환산법칙(scaling law) 을 통해 계산하였다. 또한, 폭발과압으로 인한 인체 상해에 대해 폐출혈(Lung Haemorrhage)로 인한 사망과 고막파열 등의 상해를 고려하여 Probit 모델을 통하여 추정하였다. CO2 is non-flammable, non-toxic gas and not cause of chemical explosion. However, various impurities and some oxides can be included in the captured CO2 inevitably. While the CO2 gas was temporarily stored, the pressure in a storage tank would be reached above 100bar. Therefore, the tank could occur a physical explosion due to the corrosion of vessel or uncertainty. Evaluating the intensity of explosion can be calculated by the TNT equivalent method generally used. To describe the physical explosion, it is assumed that the capacity of a CO2 temporary container is about 100 tons. In this work, physical explosion damage in a CO2 storage tank is estimated by using the Hopkinson's scaling law and the injury effect of human body caused by the explosion is assessed by the probit model.

Dynamic Response of High Strength Steel Beams Subjected to Explosion Induced Blast Load

Xinchang Feng,Xiyue Liu,Zhiyang He,Shuxin Bai,Shun Li,Yu Tang 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.6

A series of anti-explosion tests were performed on H-type high strength steels (Q460JSC and HQ600) and ordinary steels (Q345B) to address the problem of anti-explosion in the technical application of high strength steel. The dynamic behavior of steel beams during explosion and the propagation of shock waves were analyzed. The effects of proportionate distance, steel strength, high-span ratio, section shapes were investigated. The finite element software (ANSYS/LS-DYNA) was used to analyze the anti-explosion performance of high strength steel beams. The finite element models which adopted modified Johnson–Cook constitutive model and damage criterion were validated by comparing with the experimental results. The influence factors of anti-explosion performance of high strength steel were explored by numerical simulation as well. The results reveal that under near-explosion conditions, the peak values of overpressure predicted by empirical formulas are often less than the experimental outcomes. As the scaled distance reduces, the damage to the steel beam increases, making it more prone to local fracture. By decreasing the scaled distance, increasing the high-span ratio, and strengthening the constraint of H-type steel beam, the deformation and damage of steel beams can reduce. The results provide an effective basis to evaluate the safety of high strength steel beams applied in practical engineering when subjected to explosion.

A Study on the Structure Response of Explosion Simulation Models for the Evaluation of Explosive Threats to Nuclear Power Plants

Eojin Jeon,Wooseub Kim,Hyeseung Kim,Sundo Choi 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Nuclear power plants, which are important national facilities, require special attention against the threat of terrorism using various methods. Among the terrorist threats, as structural damage and human casualties due to explosions continue to occur, interest in the blast load is increasing. However, domestic nuclear power plants do not have sufficient design requirements for protection against the threat of explosives. To prepare for the threat of terrorism using explosives, it is necessary to evaluate the physical protection performance of nuclear power plants against blast load, and to use this to improve protection performance and establish regulatory standards. Most of the explosion-proof designs used abroad use the empirical chart presented by UFC 3-340- 02 (DoD 2008), which does not take into account the effect of near-field explosions. When explosions occur inside nuclear power plants, near-field explosions occur in most cases. In this study, it was assumed that explosives were installed in the corridor inside nuclear power plants. A spherical TNT was placed in the middle of the corridor floor to simulate near-field explosions, and the structure response according to the weight of the TNT was evaluated. The corridor was modeled with a reinforced concrete material and the LS-DYNA program was used for analysis. For the explosion model, the Arbitrary-Lagrangian-Eulerian (ALE) analysis technique applying the advantages of the Lagrangian and Eulerian methods were used. By analyzing the pressure history and the degree of deformation of the structure according to the explosion, the degree of threat caused by the explosion was analyzed. Based on the analysis of this study, physical barriers performance database (DB) using Modeling & Simulation (M&S) will be constructed by performing sensitive analysis such as representative structure shape setting, boundary conditions, material of structures, etc. The constructed DB is expected to be used to establish regulatory standards for the physical barriers of nuclear power plants related to explosives.

주택가격의 폭발적 거품의 추정

조무상(Moo-Sang Cho),남주하(Joo-Ha Nam) 한국주택학회 2019 주택연구 Vol.27 No.1

본 연구는 주택가격에 있어 내재가치(intrinsic value)와 시장가격 간의 괴리로 정의되는 거품항을 정보착오모형(information error model)을 이용하여 측정하고 이 거품항에 대한 생존 분석(survival analysis)을 통해 폭발적 거품의 존재유무를 분석한다. 정보착오모형의 종속변수는 주택매매가격지수이고 설명변수로는 주택전세가격지수 또는 매매전세비율을 사용한다. 생존 분석은 거품의 생존기간이 시장기초요소와 무관함을 가정하는 외생적 거품모형과 시장기초요소에 의해 거품의 생존기간이 영향을 받는 것을 가정하는 내생적 거품모형을 대상으로 수행한다. 분석대상지역은 전국, 6대광역시, 서울강남, 서울강북의 4개 지역에 대해, 1987년 1월∼2017년 12월의 기간 및 6개 하부기간에 대해 분석을 수행하였다. 분석결과, 외생적 거품모형에서는 어떠한 시간적 범위 또는 공간적 범위에서도 폭발적 거품의 존재를 찾을 수 없었다. 내생적 거품 모형에서는 형태모수 α값이 대부분 1보다 크지만 2보다는 작은 것으로 나타났다. 외생적 거품 모형과 내생적 거품모형 모두에서 폭발적 거품의 존재를 확인할 수 없었다. 이는 주택가격에 안정적 거품은 존재하지만 폭발적 거품은 존재하지 않으며 내재가치 간의 괴리는 시간의 흐름에 따라 소멸됨을 시사한다. This study examines the existence of explosive bubbles in house prices. Even if there is a bubble in the house prices, as long as it is not explosive, we can not conclude that there exists a bubble only based on the fact that house prices soar or are too high because house prices can be restored to a proper level after a certain period of adjustment. Therefore, using Information Error model, we measure the bubble term, which is defined as the gap between the intrinsic value explained by the market fundamentals and the market price, and then check whether there is an explosive bubble by Survival analysis. Housing Sales Price Index as a dependent variable, and explanatory variables such as not only Jeonse Price Index but also Sales-Jeonse Prices ratio, which reflect properly the relation between sales and rental prices, are included for Information Error model. Survival analysis is performed by an exogenous as well as an endogenous bubble model. Survival times of bubbles are assumed to be independent of market fundamentals in exogenous bubbles model while dependent in endogenous bubbles model. Samples are the period from January 1987 to December 2017 and six sub sample periods. Regional ranges are for the four regions of the whole country, the six metropolitan cities, Seoul Gangnam, and Seoul Gangbuk. For the exogenous bubbles model, Not in the whole sample nor any sub-samples, the existence of explosive bubbles was found. For the endogenous bubbles model in which ‘interest rate’ are used as market fundamental variables, shape parameter α is estimated to be 1<α <2. Values of the shape parameter, α, with larger than 2 are not found in both of exogenous and endogenous bubbles model of Survival analysis, so we can not find any evidence supporting existence of explosive bubbles. It implies that there are no explosive but stable bubbles in any sub-sample, and the bubbles become extinct over time.

내부 폭발에 의한 함정의 손상 예측

장원준,정준모 대한조선학회 2024 大韓造船學會 論文集 Vol.61 No.1

In order to reasonably predict damage extents of naval ships under in-compartment explosion (INCEX) loads, two conditions should be fulfilled in terms of accurate INCEX load generation and fracture estimation. This paper seeks to predict damage extents of various naval ships by applying the CONWEP model to generate INCEX loads, combined with the Hosford-Coulomb (HC) and localized necking (LN) fracture model. This study selected a naval ship with a 2,000-ton displacement, using associated specifications collected from references. The CONWEP model that is embedded in a commercial finite element analysis software ABAQUS/Explicit was used for INCEX load generation. The combined HC-LN model was used to simulate fracture initiation and propagation. The permanent failures with some structural fractures occurred where at the locations closest to the explosion source points in case of the near field explosions, while, some significant fractures were observed in way of the interfaces between bulkheads and curtain plates under far field explosion. A large thickness difference would lead to those interface failures. It is expected that the findings of this study enhances the vulnerability design of naval ships, enabling more accurate predictions of damage extents under INCEX loads.

CO<SUB>2</SUB> 임시 저장 탱크에서의 물리적 폭발에 따른 피해영향 고찰

서두현(Doo-Hyoun Seo),장갑만(Kap-Man Jang),이진한(Jin-Han Lee),이광원(Kwang-Won Rhie) 한국가스학회 2015 한국가스학회지 Vol.19 No.2

CCS(Carbon Dioxide Capture and Storage)은 온실가스의 주원인 중 하나인 CO<SUB>2</SUB>를 감축하기 위한 대안으로 발전, 시멘트 및 철강 산업 등에서 발생하는 대량의 CO<SUB>2</SUB>를 포집, 압축·액화하여 저장소에 격리하는 일련의 전 과정을 말한다. 이때, 포집된 CO<SUB>2</SUB>는 수송 과정 전·후에 임시저장소에 저장 하게 된다. CO<SUB>2</SUB>는 일반적으로 비 가연성, 무독성가스로 저장소에서 화학적 폭발을 일으킬 가능성이 희박한 가스지만, 임시로 저장되어 보관될 동안 100bar이상의 압력으로 보관되고 있으며, 포집된 가스에 포함된 불순물과 산화물 등에 의해 용기의 부식으로 인한 물리적 폭발이 일어날 가능성이 있다. 폭발 강도는 일반적으로 TNT 상당질량을 통해 계산할 수 있으며, CO<SUB>2</SUB> 임시 저장소는 대량의 CO<SUB>2</SUB>를 보관하기 위한 시설로 용기의 용량을 100,000L(100톤)로 가정하여 계산하였다. 계산을 통하여 약 100bar로 압축되어 저장된 100톤의 임시저장소 1개가 폭발할 때의 폭발위력을 산출하면, 대략 2346 lb 이며, 이를 환산하면 약 1064 kg의 TNT가 폭발하는 위력과 동일한 것으로 계산된다. 폭발중심으로부터의 거리에 따른 과압은 환산법칙(scaling law)을 통해 계산하였다. 또한, 폭발과압으로 인한 인체 상해에 대해 폐출혈(Lung Haemorrhage)로 인한 사망과 고막파열 등의 상해를 고려하여 Probit 모델을 통하여 추정하였다. CO<SUB>2</SUB> is non-flammable, non-toxic gas and not cause of chemical explosion. However, various impurities and some oxides can be included in the captured CO<SUB>2</SUB> inevitably. While the CO<SUB>2</SUB> gas was temporarily stored, the pressure in a storage tank would be reached above 100bar. Therefore, the tank could occur a physical explosion due to the corrosion of vessel or uncertainty. Evaluating the intensity of explosion can be calculated by the TNT equivalent method generally used. To describe the physical explosion, it is assumed that the capacity of a CO<SUB>2</SUB> temporary container is about 100 tons. In this work, physical explosion damage in a CO<SUB>2</SUB> storage tank is estimated by using the Hopkinsons scaling law and the injury effect of human body caused by the explosion is assessed by the probit model.