Simulation Analysis of Indoor Gas Explosion Damage

Journal of Beijing Institute of Technology 2003, Vol. 12, No. 3Simulation Analysis of Indoor Gas Explosion DamageQIAN Xin-ming(钱新明),( HEn Lin-shun(陈林顺), FENG Chang-gerf冯长根)State Key laboratory of Explnd Safety Science, Beijing Institute of Technology Beijing 100081, ChinaAbstract: The influence factors and process of indoor gas explosion are studied with AutoRea Gas explosion simulator. The result shows that venting pressure has great influence on the indoor gas explosion damage. The higherthe venting pressure is the more serious the hazard consequence will be. The ignition location has also evident effect on the gas explosion damage. The explosion static overpressure would not cause major injury to person andious damage to structure in the case of low venting pressure( lower than 2 kPa ) The high temperature combustion after the explosion is the major factor to person injury in indoor gas explosion accidentsre high temperature coCLC number: X 928.03 Document code: A Article ID: 1004-0579( 2003 )3-0286-04With the cities expansion in China more and used as the important reference on how to prevent andmore rural areas have been developed into towns and decrease the occurrence of indoor gas explosionsmall cities. Therefore the amount of fuel gas conControl equations Combustion1 Gas Explosion andsuming increases sharply. The cities residentsused to using gas instead of coal as family fuel. Theuse of gas makes the cities more clean and neatGas explosion can be modeled as whole gas exHowever on the other hand the number of gas exat inputcs canplosion accidents increased largely. Especially the in-be computed with a set of mass momentum and endoor gas explosion accidents happen so frequentlyergy conservation equations. They can be written bywhich cause lots of property loss and fatalities IJUnfortunately there are few research reports onMass conservation equationindoor gas explosion even though theso serious. Xiong Zhikun of Tsinghua University analyzed and assessed the hazard of using gas in cities andMomentum conservation equation istowns. Yue Hong evaluated the influence of civil gasexplosion on building structure. Gao Jian presented(2)some countermeasures on how to decrease the strucEnergy conservation equation ispor gas explosion. All thebove-mentioned studies used empirical methods toE)+(cE)=calculate the overpressure induced by indoor gas exDEplosion and they mainly focus on the influence of in(3)door gas explosion on building structure 231Fuel mass fractiethe indoor gas explosion process in a typical Chinese中国煤化工3(rm)+Rcivil one-bed room apartment. The results can beTHCNMHG(4)Received 2003-03-28BiographyQIANXin-ming(1967-)associateprofessor,semon@bit.edu.cnQIAN Xin-ming( #wT BA ) et al. Simulation Analysis of Indoor Gas Explosion damageThe key factor in gas explosion mechanism is the such as furniture etc. Figure 2 is the 3-D simulationturbulent flow which can be depicted with k-e model in which WI to w6 represent the vent areasmodel, here k is turbulent flow kinetic energy ande. the location and the areas of windows The folis turbulent flow dissipation rate. We havelowing two conditions are considered during simula0(m)+1(P)(r)+tion with above model(5)and the dissipation rate equation in turbulent flow kinetic energy Isa(:)+y axC2,(6)。Ntr=以(ax+ax)-3队+)(7where p is the density u; is the flow velocity along icoordinates, p is the static pressure, E is the energy K is the turbulent flow kinetic energy e is thedissipation rate of turbulent flow kinetic energy mfis the fuel mass fraction u, is the turbulent flow visexplosion simulation modelcosity coefficient Ru is the gas combustion rate Tis the turbulent flow viscosity coefficient in transportation characteristic, Cp is the specific heat capacity at constant pressure, T is the temperature, Hog heat ,anumber in transportation characteristicTurbulent flow intensity u and its characteristiclength Lt can be calculated by k and e(82 Auto Rea Gas simulatorFig. 2 3-D chart of venting area settingO Fixing ignition location while changing ventJointly developed by Century Dynamics of USAing pressure of indoor windows iand tno of Netherlands in 1997, AutoReagas ismodel 1. 1: ignition location is at cook roomused to analyze gas explosion field 6]and venting pressure of windows is 03 Simulation Modeand venting pressure of window is 2 kPane-bedignition location is at cook roomtaken as an example in the paper to demonstrate how中国煤化the indoor gas explosion damage is caused supposingHCN MH Gre of indoor windowsthe gas filled whole apartment and was ignited thewhile changing ignition locationThe simulation model is built as Fig. 1, where Q1 tomodel 2enting pressure of windows isQ10 are the walls while zl to Z12 are the obstacles 2 kPa, and ignition location is at cook room287一Journal of Beijing Institute of Technology 2003, Vol. 12, No. 3del 2. 2: venting pressure of windows is son of maximum overpressures at different gauges un2 kPa and ignition location is at drawing roomder three kinds of venting pressuresmodel 2. 3: venting pressure of windows is2 kPa, and ignition location is at bedroomblow-out overpressure 4 kPa4 Analysis of Simulation Results andPrediction of Damage effect1 Comparison of Damages Caused by DifferentKinds of venting Pressuresopen windoof indoor gas explosion. Take the gauge 1 as exam-81428531521404654566167pIe. When the venting pressure of windows is zerotest gauge Nopressure is 3. 46 kPa, and the time to maximum staticVenting pressure has no obvious effect on theoverpressure is 0. 48s. When the venting pressure of temperature of explosion production. At gauge 65windows is 2.00 kPa, the maximum static pressure is when the venting pressure is 0, 2 and 4 kPa, the8.20 kPa and the time to maximum static pressure is maximum temperature is 2077, 077 and 2 091 K0. 37 s. But when the venting pressure of windows is respectively while the time to maximum static pres4.00 kPa, the maximum static pressure reaches sure is 0.95,0.37 and 0. 34 s. Figure 5 illustrates14.80 kPa and the time to maximum static pressure the above resultsis 0. 35s. It can be deduced that the more the vent2200ing pressure is the more the static pressure at gaugeis and the shorter the time reaching maximum static 3 400pressure is. More serious explosion occurs with the21000ow-out overpressure 2 kPaincreasing of venting pressure. Figure 3 shows theblow-out overpressure 4 koverpressure-time curve of gauge I under three condi.tions. The reason that curves drops sharply afterreaching peak is the windows are broken and penetrated under peak overpressure therefore the pressureindoor decapidly. Figure 4 lists the compariFig 5 Explosion temperature-time curves of gauge 65( ignition in cookroom4.2 Analysis of Simulation Results and Predictionblow-outof Damage EffectThe paper deals with three kinds of ignition loca-ons. Igniting at cook room the coordinates of ignition location is ( 6.0, 3.5, 1.0)with model 2. 1 igniting at drawing room the coordinates of ignition lo0catid中国煤化工 model2.2 and igniting0250.500751.001CNMHG igniting is(2.0.0Fig 3 Static explosion overpressure-time curves of gauge 1It can be found that the change of ignition locaignition in cookroomtion has big influence on explosion static overpressureQIAN Xin-ming( #wT BA ) et al. Simulation Analysis of Indoor Gas Explosion damageFor the gauge 61 in cook room, when the ignition lo5 Conclusionscation is in cook room the maximum explosion staticoverpressure is 5.9 kPd 0. 340 s),9.8 kPd0505s)Some results are obtained by above simulationin drawing room and 11.6 kP 0. 612 s )in bedroom. with Auto Rea Gas on indoor gas explosionThe reason there is big difference in maximum exploThe venting pressure has huge effect on indoorsion overpressure is the change of relative location of gas explosion damage. Under the assumed boundarygauge with respect to ignition. Therefore the distance conditions when the venting pressure is 0 kPa, i.efrom ignition to gauge changes in case of igniting. windows are open the indoor gas explosion can causeThe added indoor obstacles such as wall and furniture no damage to structure but only to windows. Whencause turbulent flow which enhances the explosion venting pressure is 2 kPa, the apartment will be parteffect. All those contribute the different overpressures ly damaged while the ventirsure is 4 kPa, theto the same gauge. The comparison of overpressure- apartment will be more seriously damaged but will nottime curves at gauge 61 under three kinds of ignition be demolishedconditions is shown in Fig. 6The overpressure owing to indoor gas explosion12has no serious injury to person But it can cause perignition in cookroom(6.0, 3.5, 1.0)son's light injury in some special indoor areaUnder the boundary conditions the paperignition in bedroom(2.0, 2.0, 1.0)sumed if indoor gas explosion occurs the explosiontemperature can reach 2 000 K within 0.2-0.8 sand this high temperature can last about 1 s. Therefore the high temperature burning is the main reason02040.60.8141.61.8for persons injury caused by indoor gas explosionReferencesFig 6 Static explosion overpressure-time curves of gauge1] Chen Linshun. The analysis and simulation of BLEVEThe ignition location has little influence on exand VCE accident[ D]. Beijing: School of MechatronicsEngineering, Beijing Institute of Technology 2001 ( inplosion temperature. For example for gauge 56, themaximum temperature under three kinds of ignition [2] Yue Hong. Effect analysis of civil gas explosion on buildconditions are 2 073K(0. 381 s)2053 K(0. 509 s)ing structurd D ] Beijing: Department of Civil Engineernd 2 056K(0.617 s) respectively. The results showing, Tsinghua University, 1997. in Chinesethat the explosion temperature is in sensitive to the [3] Gao Jian. Damage and countermeasures of indoor gas ex-ignition location( see Fig. 7)plosion to civil building[ D ] Beijing: Department of Civ2200il Engineering Tsinghua University, 1999.( in Chinese)[4] Century Dynamics and TNO. The interactive softwarefor reactive gas dynamic and blast analysi M]. Bostonignition in drawing room(2.0, 6.0, 1.0)Century Dynamics and TNO, 1996ignition in bedroom(2.0, 2.0. 1.0)[5] Qian Xinming, Chen Lang, Feng Changgen, et al. Onsimulation of explosion accident[ A ]. Progress in Safety中国煤化工Ⅲ[C] Beijing: Chemical0.204060.81.012141.61.8[6]CNMHAs-A code for numericalsimulation of 2-D reactive gas dynamics in gas explosionsFig 7 Explosion temperature-time curves of gauge 56[R I TNO Prins Maurits Laboratory report No. PMLblow-out overpressure 2 kPa1989-IN48,198289