低气压环境对固体燃烧特性影响的实验研究
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摘要
飞机货舱火灾已成为巡航飞机的主要安全威胁之一,它的发生会造成巨大的财产和人员伤亡。该文以航空货运中常见的瓦楞纸箱为对象,在低压舱中开展了不同数量纸箱火(纸箱火可代表A类固体火)实验,测量了燃烧过程中的质量燃烧速率、火焰轴向辐射热通量和火焰温度等特征参量。首先,采用修正的B-number理论,从传热传质角度推导低气压对固体燃烧速率行为的影响规律;其次,分析了不同纸箱放置情况下,火焰辐射热通量和中心线温度分布的变化规律。结果表明:湍流固体火灾燃烧速率的压力表达式为m″∝C_hP~(2/3)+C_rP~(3/2),进而通过实验验证了该表达式,同时给出经验关系式m∝P~(1.3);发现辐射热通量整体上呈先升高后下降趋势,R2的辐射热通量相比其他位置更大;火焰温度最大值为800℃,位于火焰的连续区。该文从理论和实验两方面揭示了不同低压环境下固体燃料的火灾行为特征,为航空火险救援提供依据。
Cargo compartment fire has become the major security threat for cruising aircraft that can cause huge property and casualties.The effects of low pressures on common solid fuel fire behavior in air freight was studied using different amounts of corrugated cartons can represent typical Class A solid fuel fires.Mass burning rate,radiative heat flux,and flame axial temperature had been measured as the principal characteristic parameters during the combustion process. The modified B-number theory was employed to model the burning rate behavior of solid fuel.The theoretical relationship between the burning rate and the ambient pressure for a turbulent solid fuel fire is m″∝C_hP~(2/3)+C_rP~(3/2).The experimental results showed that the modified pressure index is 1.3.In addition,the flame radiant heat flux and centerline temperature distribution were analyzed to indicate that the radiant heat flux first increased and then decreased.The radiant heat flux at the R2 location was greater than at other locations.The maximum flame temperatures was 800℃ in the flame zone.The solid fuel fire behavior under reduced pressure environment was investigated from both theoretical and experimental aspects,which provided a basis for aviation fire insurance.
Cargo compartment fire has become the major security threat for cruising aircraft that can cause huge property and casualties.The effects of low pressures on common solid fuel fire behavior in air freight was studied using different amounts of corrugated cartons can represent typical Class A solid fuel fires.Mass burning rate,radiative heat flux,and flame axial temperature had been measured as the principal characteristic parameters during the combustion process. The modified B-number theory was employed to model the burning rate behavior of solid fuel.The theoretical relationship between the burning rate and the ambient pressure for a turbulent solid fuel fire is m″∝C_hP~(2/3)+C_rP~(3/2).The experimental results showed that the modified pressure index is 1.3.In addition,the flame radiant heat flux and centerline temperature distribution were analyzed to indicate that the radiant heat flux first increased and then decreased.The radiant heat flux at the R2 location was greater than at other locations.The maximum flame temperatures was 800℃ in the flame zone.The solid fuel fire behavior under reduced pressure environment was investigated from both theoretical and experimental aspects,which provided a basis for aviation fire insurance.
引文
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[23]WIESER D,JAUCH P,WILLI U.The influence of high altitude on fire detector test fires[J].Fire Safety Journal,1997,29(2-3):195-204.
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[27]GONG J H,YANG L Z,ZHOU X D,et al.Effects of low atmospheric pressure on combustion characteristics of polyethylene and polymethyl methacrylate[J].Journal of Fire Sciences,2012,30(3):224-239.
[28]HU L H, TANG F, WANG Q, et al. Burning characteristicsofconduction-controlledrectangular hydrocarbon pool fires in a reduced pressure atmosphere at high altitude in Tibet[J].Fuel,2013,111:298-304.
[29]TU R,FANG J,ZHANG Y M,et al.Effects of low air pressure on radiation-controlled rectangular ethanol and n-heptane pool fires[J].Proceedings of the Combustion Institute,2013,34(2):2591-2598.
[30]HU L, WANG Q,DELICHATSIOS M,et al.Flame radiation fraction behaviors of sooty buoyant turbulent jet diffusion flames in reduced-and normal atmospheric pressures and a global correlation with Reynolds number[J].Fuel,2014,116:781-786.
[31]TANG F, HU L H,YANG L Z,et al.Longitudinal distributions of CO concentration and temperature in buoyant tunnel fire smoke flow in a reduced pressure atmosphere with lower air entrainment at high altitude[J].International Journal of Heat and Mass Transfer,2014,75:130-134.
[32]HUANG X J,ZHAO J,TANG G,et al.Effects of altitude and inclination on the flame structure over the insulation material PS based on heat and mass transfer[J].International Journal of Heat and Mass Transfer,2015,90:1046-1055.
[33]YAO J J,LIU J H,CHEN X,et al.Experimental study of small scale n-heptane pool fire with water bath in an altitude chamber[J].International Journal of Heat and Mass Transfer,2015,90:1153-1159.
[34]MOST J M,MANDIN P,CHEN J,et al.Influence of gravity and pressure on pool fire-type diffusion flames[C]//Symposium(International)on Combustion.Pittsburgh,PA,USA:The Combustion Institute,1996,26(1):1311-1317.
[35]HAMINS A P,YANG J C,KASHIWAGI T.Global model for predicting the burning rates of liquid pool fires(NISTIR 6381)[S].Gaithersburg,MD,USA:NIST Interagency,1999.
[36]QUINTIERE J G.Fundamentals of fire phenomena[M].Chichester,United Kingdom:John Wiley&Sons,2006.
[37]INCROPERA F P,DEWITT D P.Introduction to heat transfer[M]. New York, NY, USA:John Wiley&Sons,1996.
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[39]REINHARDT J W,BLAKE D,MARKER T.Development of a minimum performance standard for aircraft cargo compartment gaseous fire suppression systems[S].Atlantic City, NJ, USA:FAA Technical Center Fire Safety Section,2000.
[40]KANURY A M.Modeling of pool fires with a variety of polymers[C]//Symposium(international)on Combustion.Pittsburgh,PA,USA:The Combustion Institute,1975,15(1):193-202.
[41]LOCKWOOD R,CORLETT R.Radiative and convective feedback heat flux in small turbulent pool fires with variable pressure and ambient oxygen[C]//Proceedings of the 1987ASME-JSME Thermal Engineering Joint Conference.New York, NY, USA:American Society of Mechanical Engineers,1987.
[42]SHINOTAKE A,KODA S,AKITA K.An experimental study of radiative properties of pool fires of an intermediate scale[J]. Combustion Science and Technology,1985,43(1-2):85-97.
[43]MCCAFFREY B J.Purely buoyant diffusion flames:Some experimental results(NBSIR-79-1910)[S].Washington DC,USA:National Bureau of Standards,1979.
[2] Cabin Safety Research Technical Group.CSRTG aircraft accident database[EB/OL].(2012-07-05).[2018-04-30].https://www.fire.tc.faa.gov/adb/adb/ADBlist.asp.
[3] WIKIPEDIA. Aviation accidents and incidents[EB/OL].(2012-07-05)[2018-04-30]. http://en.wikipedia.org/wiki/Category:Aviation_accidents_and_incidents_in_2012.
[4] FANG J,YU C Y,TU R,et al.The influence of low atmospheric pressure on carbon monoxide of n-heptane pool fires[J]. JournalofHazardousMaterials, 2008,154(1):476-483.
[5] LI Z,HE Y,ZHANG H,et al.Combustion characteristics of n-heptane and wood crib fires at different altitudes[J].Proceedings of the Combustion Institute,2009,32(2):2481-2488.
[6] FANG J,TU R,GUAN J F,et al.Influence of low air pressure on combustion characteristics and flame pulsation frequency of pool fires[J].Fuel,2011,90(8):2760-2766.
[7] HU X K,HE Y P,LI Z H,et al.Combustion characteristics of n-heptane at high altitudes[J].Proceedings of the Combustion Institute,2011,33(2):2607-2615.
[8] FERERES S,LAUTENBERGER C,FERNANDEZ-PELLO A C,et al.Understanding ambient pressure effects on piloted ignition through numerical modeling[J].Combustion and Flame,2012,159(12):3544-3553.
[9] NIU Y,HE Y P,HU X K,et al.Experimental study of burning rates of cardboard box fires near sea level and at high altitude[J].Proceedings of the Combustion Institute,2013,34(2):2565-2573.
[10]YAO W,HU X K,RONG J Z,et al.Experimental study of large-scale fire behavior under low pressure at high altitude[J].Journal of Fire Sciences,2013,31(6):481-494.
[11]YIN J S,YAO W,LIU Q Y,et al.Experimental study of n-heptane pool fire behavior in an altitude chamber[J].International Journal of Heat and Mass Transfer,2013,62:543-552.
[12]ZHOU Z H,WEI Y,LI H H,et al.Experimental analysis of low air pressure influences on fire plumes[J].International Journal of Heat and Mass Transfer,2014,70:578-585.
[13]FERERES S,FERNANDEZ-PELLO C,URBAN D L,et al.Identifying the roles of reduced gravity and pressure on the piloted ignition of solid combustibles[J].Combustion and Flame,2015,162(4):1136-1143.
[14]LIU J H,HE Y P,ZHOU Z H,et al.The burning behaviors of pool fire flames under low pressure[J].Fire and Materials,2016,40(2):318-334.
[15]TU R,ZENG Y,FANG J,et al.Low air pressure effects on burning rates of ethanol and n-heptane pool fires under various feedback mechanisms of heat[J].Applied Thermal Engineering,2016,99:545-549.
[16]MA Q J,LIU Q Y,ZHANG H,et al.Experimental study of the mass burning rate in n-heptane pool fire under dynamic pressure[J]. AppliedThermalEngineering, 2017,113:1004-1010.
[17]BABRAUSKAS V.Estimating large pool fire burning rates[J].Fire Technology,1983,19(4):251-261.
[18]IQBAL N, SALLEY M H, WEERAKKODY S. Fire dynamics tools(FDTs):Quantitative fire hazard analysis methods for the US nuclear regulatory commission fire protection inspection program[S].Washington DC,USA:Nuclear Regulatory Commission,2004.
[19]DE RIS J,KANURY A M,YUEN M.Pressure modeling of fires[C]//Symposium(International)on Combustion.Pittsburgh,PA,USA:The Combustion Institute,1973,14(1):1033-1044.
[20]ALPERT R.Pressure modeling of transient crib fires[J].Combustion Science and Technology,1977,15(1-2):11-20.
[21]ALPERT R. Pressure modeling of fires controlled by radiation[C]//Symposium(International)on Combustion.Pittsburgh,PA,USA:The Combustion Institute,1977,16(1):1489-1500.
[22]DE RIS J L,WU P K,HESKESTAD G.Radiation fire modeling[J].Proceedings of the Combustion Institute,2000,28(2):2751-2759.
[23]WIESER D,JAUCH P,WILLI U.The influence of high altitude on fire detector test fires[J].Fire Safety Journal,1997,29(2-3):195-204.
[24]刘勇.高原环境对火灾早期燃烧特性及火灾探测影响的研究[D].合肥:中国科学技术大学,2006.LIU Y.Study on the influence of plateau environment on early combustion characteristics and fire detection[D].Hefei:University of Science and Technology of China,2006.(in Chinese)
[25]XIN Y,KHAN M M.Flammability of combustible materials in reduced oxygen environment[J].Fire Safety Journal,2007,42(8):536-547.
[26]LI J,JI J,ZHANG Y,et al.Characteristics of flame spread over the surface of charring solid combustibles at high altitude[J].Chinese Science Bulletin,2009,54(11):1957-1962.
[27]GONG J H,YANG L Z,ZHOU X D,et al.Effects of low atmospheric pressure on combustion characteristics of polyethylene and polymethyl methacrylate[J].Journal of Fire Sciences,2012,30(3):224-239.
[28]HU L H, TANG F, WANG Q, et al. Burning characteristicsofconduction-controlledrectangular hydrocarbon pool fires in a reduced pressure atmosphere at high altitude in Tibet[J].Fuel,2013,111:298-304.
[29]TU R,FANG J,ZHANG Y M,et al.Effects of low air pressure on radiation-controlled rectangular ethanol and n-heptane pool fires[J].Proceedings of the Combustion Institute,2013,34(2):2591-2598.
[30]HU L, WANG Q,DELICHATSIOS M,et al.Flame radiation fraction behaviors of sooty buoyant turbulent jet diffusion flames in reduced-and normal atmospheric pressures and a global correlation with Reynolds number[J].Fuel,2014,116:781-786.
[31]TANG F, HU L H,YANG L Z,et al.Longitudinal distributions of CO concentration and temperature in buoyant tunnel fire smoke flow in a reduced pressure atmosphere with lower air entrainment at high altitude[J].International Journal of Heat and Mass Transfer,2014,75:130-134.
[32]HUANG X J,ZHAO J,TANG G,et al.Effects of altitude and inclination on the flame structure over the insulation material PS based on heat and mass transfer[J].International Journal of Heat and Mass Transfer,2015,90:1046-1055.
[33]YAO J J,LIU J H,CHEN X,et al.Experimental study of small scale n-heptane pool fire with water bath in an altitude chamber[J].International Journal of Heat and Mass Transfer,2015,90:1153-1159.
[34]MOST J M,MANDIN P,CHEN J,et al.Influence of gravity and pressure on pool fire-type diffusion flames[C]//Symposium(International)on Combustion.Pittsburgh,PA,USA:The Combustion Institute,1996,26(1):1311-1317.
[35]HAMINS A P,YANG J C,KASHIWAGI T.Global model for predicting the burning rates of liquid pool fires(NISTIR 6381)[S].Gaithersburg,MD,USA:NIST Interagency,1999.
[36]QUINTIERE J G.Fundamentals of fire phenomena[M].Chichester,United Kingdom:John Wiley&Sons,2006.
[37]INCROPERA F P,DEWITT D P.Introduction to heat transfer[M]. New York, NY, USA:John Wiley&Sons,1996.
[38]CORNER, ISOROOM. InternationalStandard-fire tests-full-scale room test for surface products;ISO 9705:1993.International Organisation for Standardisation[Z].Geneva, Switzerland:InternationalOrganisationfor Standardisation,1993.
[39]REINHARDT J W,BLAKE D,MARKER T.Development of a minimum performance standard for aircraft cargo compartment gaseous fire suppression systems[S].Atlantic City, NJ, USA:FAA Technical Center Fire Safety Section,2000.
[40]KANURY A M.Modeling of pool fires with a variety of polymers[C]//Symposium(international)on Combustion.Pittsburgh,PA,USA:The Combustion Institute,1975,15(1):193-202.
[41]LOCKWOOD R,CORLETT R.Radiative and convective feedback heat flux in small turbulent pool fires with variable pressure and ambient oxygen[C]//Proceedings of the 1987ASME-JSME Thermal Engineering Joint Conference.New York, NY, USA:American Society of Mechanical Engineers,1987.
[42]SHINOTAKE A,KODA S,AKITA K.An experimental study of radiative properties of pool fires of an intermediate scale[J]. Combustion Science and Technology,1985,43(1-2):85-97.
[43]MCCAFFREY B J.Purely buoyant diffusion flames:Some experimental results(NBSIR-79-1910)[S].Washington DC,USA:National Bureau of Standards,1979.