本文選題：船舶艙室火災(zāi) + 頂部開口��； 參考：《中國科學(xué)技術(shù)大學(xué)》2014年博士論文

【摘要】：火災(zāi)是船舶災(zāi)難性事故之一,可能導(dǎo)致嚴(yán)重的船舶損傷和人員傷亡。認(rèn)識開口與火源位置對船舶艙室火災(zāi)的影響是船舶安全工程的重要內(nèi)容,可為船舶安全設(shè)計、火災(zāi)預(yù)防和撲救等提供基礎(chǔ)數(shù)據(jù)和理論支撐。為了研究開口與火源位置對船舶艙室火災(zāi)的影響,本文針對不同火源和開口位置下的頂部開口腔室火災(zāi),以及無豎直開口腔室中的火源抬升行為開展了實驗研究和理論分析。提出了一系列船舶艙室火災(zāi)參數(shù)預(yù)測模型并對其影響因素進行了表征。本文實驗條件下得到的主要結(jié)論如下： 分析了頂部開口腔室中火源水平位置(火源XY因素)對火災(zāi)行為的影響。在頂部中央開口腔室中,將火源移離地板中央會增長穩(wěn)定燃燒時間并降低火源平均質(zhì)量損失速率,燃燒全過程的艙內(nèi)氧氣濃度空間平均值和火源平均燃燒效率均會降低。不同火源位置下頂部開口臨界尺寸存在顯著差異。火源燃燒效率隨火源區(qū)氧氣濃度的時平均值的升高而線性增大。建立了可用于比較不同熱釋放速率池火的無量綱火焰高度。頂部開口腔室池火存在火焰拉伸現(xiàn)象；以中央火為基準(zhǔn)參考,其他位置火焰存在“拉伸”行為和卷吸受限。建立了反應(yīng)腔室蓄熱能力、可用于比較不同位置火源下腔室溫升的無量綱溫升參數(shù)。當(dāng)火源位于開口正下方時,無量綱溫升最小。對于水平位置不同的火源,不同的卷吸率和離頂部開口的距離是影響其火災(zāi)行為的兩大因素。腔室內(nèi)平均煙氣密度隨頂部開口尺寸的增大而減小,中央火的下降趨勢較墻壁火和墻角火更為明顯。由于具有更大的熱釋放速率,中央火的腔室煙氣填充速率更快。影響中央火的主導(dǎo)因素為熱反饋增強,墻角火占主導(dǎo)地位的因素為氧氣受限,而墻壁火受“熱反饋增強和氧氣受限”共同作用。 研究了頂部開口腔室的開口位置(開口XY因素)對火災(zāi)行為的影響。頂部中央開口腔室火源質(zhì)量損失速率略大于頂部拐角開口腔室火源質(zhì)量損失速率,其火源燃燒效率和熱釋放速率均高于頂部拐角開口腔室火源對應(yīng)值。不同開口位置情況下的火焰拉伸特性無明顯差異。由于蓄熱性較頂部拐角開口腔室差,頂部中央開口腔室無量綱溫升低于頂部拐角開口腔室無量綱溫升。當(dāng)頂部開口遠離火源上方,其室內(nèi)的氧氣受限作用和熱反饋效應(yīng)將增強。頂部開口腔室中的平均溫升速率隨火源面積指數(shù)增大,對應(yīng)的頂部中央開口腔室的指數(shù)大于頂部拐角開口腔室的指數(shù)。頂部中央開口腔室平均煙密度隨頂部開口尺寸的增大而降低,而頂部拐角開口腔室的平均煙密度則基本保持不變。頂部拐角開口腔室中的煙氣填充速度比頂部中央開口腔室煙氣填充速度慢。采用恒定火源功率對開口位置的影響進行了數(shù)值模擬研究,數(shù)值模擬結(jié)果與對實驗結(jié)果進行無量綱分析得出的結(jié)論一致。 揭示了頂部開口或無開口腔室中抬升火源(Z因素)的行為規(guī)律。(1)揭示了頂部開口腔室中抬升火源的行為特性。當(dāng)火源抬升高度較高時,其質(zhì)量損失速率變小且穩(wěn)定燃燒時間變長。抬升火源情況下頂部開口腔室中的煙氣消光系數(shù)、氧氣濃度和氣體溫度等火災(zāi)環(huán)境參數(shù)具有明顯的分層特性。對于較高位置的火源,其煙氣沉降速率較慢。(2)揭示了抬升火源情況下無開口封閉腔室典型煙氣填充過程。煙氣消光系數(shù)、氧氣濃度和氣體溫度分布均呈現(xiàn)明顯分層,且分層界面為火源高度平面。在抬升火源情況下的無開口封閉腔室中,煙氣層沉降并滯止于火源高度平面,進而通過墻壁射流繼續(xù)煙氣填充過程。(3)可視化實驗顯示墻壁射流穿透分層平面沿著墻壁向下沉降；之后,煙氣在地板平面累積并從地板中央上升。(4)發(fā)現(xiàn)對于火源位置較高的情況,腔室內(nèi)不同高度處氧氣濃度差異較大,充分混合假設(shè)不成立。當(dāng)火焰觸頂時燃料在點燃后迅速沸騰,其燃料平均質(zhì)量損失速率遠大于開放空間自由燃燒值�；谟^測到的分層現(xiàn)象建立了氧氣消耗率的計算方法。無開口封閉腔室中抬升火源平均燃燒效率和碳轉(zhuǎn)化率隨其抬升高度線性降低�；鹧嬗|頂情況下的抬升火源在燃燒早期危害性較大�；鹧嬗|頂情況下火源平均熱釋放速率并無明顯升高。 建立了船舶A60艙室綜合傳熱系數(shù)模型、頂部開口腔室火災(zāi)溫度模型、全艙平均氧氣濃度和煙氣密度關(guān)系式等船舶艙室火災(zāi)參數(shù)預(yù)測模型,并對相關(guān)模型的影響因素進行了表征。對于船舶A60結(jié)構(gòu)艙室,其平均綜合傳熱系數(shù)與火源熱釋放速率的三分之一次方成正比。討論了對現(xiàn)有計算頂部開口傳熱方法的使用和誤用：當(dāng)火源位于開口正下方時,羽流誘導(dǎo)的頂部開口傳熱占主導(dǎo)地位。需謹(jǐn)慎應(yīng)用Cooper模型計算頂部開口傳熱。提出了當(dāng)火源位于開口正下方時的開口傳熱的處理方法。基于能量守恒和頂部開口流動經(jīng)驗關(guān)系式,推導(dǎo)建立了頂部開口腔室火災(zāi)的溫度預(yù)測模型。對于水平位置因素,其影響反映在所建立的反映“總熱釋放量與開口散失熱量比"以及“墻壁熱損失與開口散熱熱量比"的兩個無量綱量的指數(shù)上。對于移離開口正下方的火源,其溫升與火源熱釋放速率的三分之二次方成正比；對于位于開口正下方的火源,其溫升與火源熱釋放速率的三分之四次方程正比,與開口面積的六分之一次方成反比。無論是使用單區(qū)模型假設(shè)還是雙區(qū)模型假設(shè),豎直位置因素對所建立模型無顯著影響。建立了綜合腔室體積、頂部開口尺寸、開口與火源相對位置、火源熱釋放速率等因素的頂部開口腔室池火無量綱開口因子。基于無量綱開口因子,建立了全艙平均氧氣濃度關(guān)系式和全艙平均煙氣質(zhì)量密度關(guān)系式。
[Abstract]:Fire is one of the disaster accidents of a ship, which may cause serious damage and casualties. Understanding the impact of the opening and fire location on the cabin fire is an important part of the ship safety engineering. It can provide basic data and theoretical support for ship safety design, fire prevention and rescue, in order to study the location of the opening and fire source. In this paper, an experimental study and theoretical analysis are carried out on the fire in the top opening chamber under different fire sources and opening positions, as well as the uplifting behavior in the non vertical open mouth chamber. A series of prediction models for the fire parameters of the ship cabin are presented and the influencing factors are characterized. This paper is under the experimental conditions. The main conclusions are as follows:
The effect of fire source level position (fire source XY factor) on fire behavior in the top opening chamber is analyzed. In the top central open mouth chamber, moving the fire source from the center of the floor will increase the steady combustion time and reduce the average mass loss rate of the fire source. The average oxygen concentration space average in the cabin and the average combustion efficiency of the fire source will be all in the whole process of combustion. There is a significant difference in the critical size of the top opening at the top of different fire sources. The combustion efficiency of the fire source increases linearly with the increase of the time average of the oxygen concentration in the fire source area. The regenerative capacity of the reaction chamber is established, which can be used to compare the dimensionless temperature rise parameters of the chamber temperature rise under the different positions of the fire source. When the fire is located under the opening, the dimensionless temperature rise is minimal. For different fire sources with different horizontal positions, the different coiling rates and off top open. The distance of the mouth is the two factor affecting the fire behavior. The average flue gas density in the chamber decreases with the increase of the opening size of the top, and the downward trend of the central fire is more obvious than that of the wall fire and the wall angle. Feed enhancement, the main factor of corner fire is oxygen limitation, and wall fire is affected by "thermal feedback enhancement and oxygen limitation".
The effect of the opening position of the opening chamber of the top opening (XY factor) on the fire behavior is studied. The mass loss rate of the fire source in the top central open mouth chamber is slightly greater than that in the top corner of the oral chamber. The combustion efficiency and the heat release rate of the fire source are higher than the corresponding value of the open mouth chamber fire source at the top corner. There is no obvious difference in the tensile properties of the flame under the condition of the top corner opening in the mouth chamber, and there is no dimensionless temperature rise at the top of the central open mouth chamber below the top corner in the oral chamber. The average smoke density in the top central open mouth chamber decreased with the increase of the opening size of the top, while the average smoke density in the top corner opening remained unchanged. The top corner opened the smoke in the oral cavity. The velocity of gas filling is slower than that in the central open mouth chamber of the top. The influence of the constant fire power on the opening position is numerically simulated. The numerical simulation results are in agreement with the conclusion of the undimensional analysis of the experimental results.
The behavior characteristics of the elevated fire source (Z factor) in the top open or no opening chamber were revealed. (1) the behavior characteristics of the lifting fire in the top opening chamber were revealed. When the height of the fire was raised, the mass loss rate became smaller and the combustion time became longer. The smoke extinction coefficient in the top opening chamber in the top of the fire source and the concentration of oxygen were strong. The fire environment parameters, such as degree and gas temperature, have obvious stratification characteristics. For the high position fire source, the rate of flue gas settlement is slow. (2) the typical flue gas filling process without open closed chamber is revealed. The smoke extinction coefficient, oxygen concentration and gas temperature distribution are obviously stratified, and the stratified interface is fire. The source height plane. In the open closed chamber of the lift fire source, the smoke layer subsided and stagnant at the height plane of the fire source, and then the fume filling process was continued through the wall jet. (3) the visualization experiment showed that the wall jet penetrated down the wall down the wall; after that, the smoke accumulated on the floor plane and from the center of the floor. (4) (4) it is found that the oxygen concentration varies greatly at the different height of the chamber, and the full mixing assumption is not established. When the flame hits the top, the fuel is boiling quickly after the ignition. The average mass loss rate of the fuel is far greater than the free combustion value in the open space. The average combustion efficiency and carbon conversion rate of the elevated fire source in the open closed chamber are linearly decreased with the elevating height. The rising fire source at the top of the flame is more harmful in the early combustion. The average heat release rate of the fire source is not obviously increased.
The comprehensive heat transfer coefficient model of the ship's A60 cabin, the fire temperature model at the top opening chamber, the average oxygen concentration of the whole cabin and the relation of the smoke density, and so on, are used to predict the fire parameters of the ship cabin, and the influencing factors of the related models are characterized. The average comprehensive heat transfer coefficient and the heat release rate of the fire source in the ship's A60 cabin room The 1/3 time ratio is proportional. The use and misuse of the current heat transfer method at the top opening are discussed. When the fire source is located below the opening, the top opening heat transfer induced by the plume is dominant. It is necessary to use the Cooper model carefully to calculate the heat transfer at the top opening. Based on the energy conservation and the empirical relationship of the top opening flow, a temperature prediction model for the top opening chamber fire is derived. For the horizontal position factor, the effect is reflected by the two quantities that reflect the "total heat release rate and the opening heat loss ratio", and the "wall heat loss and the opening heat dissipation ratio". The temperature rise is proportional to the 2/3 square of the heat release rate of the fire source; for the fire source under the opening, the temperature rise is proportional to the 4/3 equation of the heat release rate of the fire source, and is inversely proportional to the 1/6 square of the open area. It is assumed that the vertical position factor has no significant influence on the established model. The undimensional opening factor of the oral chamber pool fire is established at the top of the chamber volume, the top opening size, the relative position of the opening and the fire source and the heat release rate of the fire source. Based on the dimensionless opening factor, the average oxygen concentration in the whole cabin is established. The relationship between the average gas mass density of the system and the whole cabin.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：U698.4

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相關(guān)期刊論文 前2條

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本文編號：1931130