高層建筑豎向通道內(nèi)煙氣輸運(yùn)規(guī)律及著火房間火行為特性研究
發(fā)布時(shí)間：2018-09-11 09:34
【摘要】：近年來(lái),我國(guó)興建了越來(lái)越多的高層建筑,且伴隨著高層建筑火災(zāi)事故頻發(fā),造成了大量的人員傷亡和財(cái)產(chǎn)損失,統(tǒng)計(jì)結(jié)果表明,火災(zāi)中有超過(guò)百分之八十的人員死亡是由于有毒煙氣造成的。高層建筑由于建筑高,撲救和控制火勢(shì)難度大,人員疏散困難。建筑內(nèi)部的豎向通道(電梯井,樓梯井,管道井)容易成為火勢(shì)迅速蔓延的重要途徑�；馂�(zāi)煙氣在高層建筑的豎向通道內(nèi)運(yùn)動(dòng)主要驅(qū)動(dòng)力有煙囪效應(yīng),湍流混合運(yùn)動(dòng),熱浮力,另外還容易受到外界風(fēng)的影響。因此研究這幾種驅(qū)動(dòng)力作用下高層建筑火災(zāi)煙氣的運(yùn)動(dòng)特性以及這幾種作用力作用下房間內(nèi)火源的燃燒,對(duì)于高層建筑火災(zāi)防治有著重要意義。 本文圍繞煙囪效應(yīng),湍流混合作用,熱浮力,外界風(fēng)等作用力,采用實(shí)驗(yàn)研究與理論分析相結(jié)合的方式,利用大空間的1：3樓梯井實(shí)驗(yàn)臺(tái)以及1：3火溢流實(shí)驗(yàn)臺(tái),開展了相應(yīng)的研究。具體工作包括： 研究煙氣前鋒在頂部開放和頂部封閉的樓梯井內(nèi)的上升時(shí)間,結(jié)合理論分析,得到煙氣前鋒上升無(wú)量綱時(shí)間與樓梯井無(wú)量綱高度的定量關(guān)系式,結(jié)果表明,開放樓梯井和封閉樓梯井內(nèi)的煙氣前鋒上升時(shí)間分別與火源功率的三分之一次方成反比,與無(wú)量綱上升高度的1.227次方和2.135次方成正比,與煙氣在豎井中的上升時(shí)間進(jìn)行對(duì)比,發(fā)現(xiàn)煙氣在樓梯井中上升比豎井中慢。開放樓梯井內(nèi)的煙氣溫度在經(jīng)歷一段時(shí)間之后,會(huì)進(jìn)入一個(gè)穩(wěn)定的階段,即樓梯井內(nèi)的溫度不隨時(shí)間變化,分析穩(wěn)定階段樓梯井內(nèi)溫度的無(wú)量綱溫升與無(wú)量綱高度的關(guān)系,發(fā)現(xiàn)無(wú)量綱溫升隨著無(wú)量綱高度的增加而指數(shù)衰減,衰減的系數(shù)近似與樓梯井內(nèi)的煙氣的質(zhì)量流量成反比,并通過(guò)實(shí)驗(yàn)數(shù)據(jù)驗(yàn)證了這一點(diǎn)。分析樓梯井溫度穩(wěn)定分布情況下內(nèi)外的壓強(qiáng)差和樓梯井開口處空氣和煙氣的流速,得到了樓梯井內(nèi)煙氣流動(dòng)的流動(dòng)系數(shù),流動(dòng)系數(shù)的值表明,樓梯井的結(jié)構(gòu)對(duì)樓梯井內(nèi)煙氣流動(dòng)的阻力非常大。 研究了煙氣在頂部封閉的豎向通道內(nèi)湍流混合作用下的運(yùn)動(dòng),前人研究封閉豎向通道內(nèi)流體湍流混合運(yùn)動(dòng)時(shí)未考慮壁面?zhèn)鳠?本文通過(guò)理論分析建立了考慮壁面?zhèn)鳠岬呢Q向通道內(nèi)流體湍流混合運(yùn)動(dòng)方程。在1：3尺寸的樓梯井實(shí)驗(yàn)臺(tái)中,開展了一系列火源產(chǎn)生的熱浮力羽流在頂部封閉的樓梯井中湍流混合運(yùn)動(dòng)實(shí)驗(yàn),并將實(shí)驗(yàn)數(shù)據(jù)與前人及本文推導(dǎo)的湍流混合運(yùn)動(dòng)方程的數(shù)值求解結(jié)果進(jìn)行對(duì)比。對(duì)比結(jié)果表明,本文提出的湍流混合運(yùn)動(dòng)方程可以較好地模擬強(qiáng)熱浮力羽流在頂部封閉的豎向樓梯井內(nèi)的湍流混合運(yùn)動(dòng),前人的模型計(jì)算的結(jié)果比實(shí)驗(yàn)值偏高。 研究了多個(gè)開口的樓梯井在火災(zāi)情況下中性面的位置,通過(guò)實(shí)驗(yàn)中測(cè)得的溫度數(shù)據(jù),風(fēng)速數(shù)據(jù)以及拍攝的視頻,判定了多開口樓梯井中性面的位置。結(jié)合樓梯井內(nèi)的溫度分布,利用流體靜力學(xué)方程,伯努利方程和質(zhì)量守恒方程,計(jì)算火災(zāi)情況下多個(gè)開口樓梯井的中性面位置,計(jì)算結(jié)果和實(shí)驗(yàn)得到的結(jié)果對(duì)比,發(fā)現(xiàn)兩者符合得較好。結(jié)果表明在相同開口狀況下,不同火源功率對(duì)樓梯井中性面位置的影響較小,火源功率較小時(shí),樓梯井中性面高度會(huì)偏低。在三個(gè)開口的樓梯井中,樓梯井的中性面位置主要由樓梯井的開口狀況決定。 利用1：3尺寸的火溢流實(shí)驗(yàn)臺(tái),研究了在著火房間熱浮力作用下,著火房間外的溢流火焰形態(tài),分析了溢流火焰在水平和豎直方向上的長(zhǎng)度,建立了火焰尺寸與火源功率以及著火房間開口狀況之間的耦合關(guān)系式,并分析了溢流火焰震動(dòng)頻率與房間開口狀況之間的關(guān)系。研究了在外界風(fēng)和著火房間熱浮力共同作用下,著火房間內(nèi)的通風(fēng)狀況,以及通風(fēng)狀態(tài)對(duì)著火房間內(nèi)燃燒的影響。
[Abstract]:In recent years, more and more high-rise buildings have been built in China, and with the frequent fire accidents in high-rise buildings, a large number of casualties and property losses have been caused. Statistics show that more than 80% of the deaths in fires are caused by toxic fumes. It is difficult to evacuate people. Vertical passages (elevator shaft, stairwell, pipeline shaft) inside buildings are easy to become important ways of rapid fire spread. The main driving forces of fire smoke in vertical passages of high-rise buildings are chimney effect, turbulent mixing motion, thermal buoyancy, and also vulnerable to the influence of external wind. The motion characteristics of fire smoke in high-rise buildings under dynamic action and the combustion of fire sources in rooms under these forces are of great significance for fire prevention and control of high-rise buildings.
In this paper, the chimney effect, turbulent mixing, thermal buoyancy, external wind and other forces are studied by combining experimental research with theoretical analysis. The corresponding research is carried out by using the 1:3 stairwell test bench with large space and the 1:3 fire overflow test bench.
The rising time of flue gas front in open and closed stairwells was studied. Based on theoretical analysis, the quantitative relationship between the dimensionless rising time of flue gas front and the dimensionless height of stairwells was obtained. The results show that the rising time of flue gas front in open stairwells and closed stairwells is one third of the fire power, respectively. Comparing with the rising time of flue gas in the shaft, it is found that the rising speed of flue gas in the stairwell is slower than that in the shaft. The relationship between dimensionless temperature rise and dimensionless height is analyzed. It is found that the dimensionless temperature rise decreases exponentially with the increase of dimensionless height. The coefficient of attenuation is inversely proportional to the mass flow rate of flue gas in the stairwell. This is verified by experimental data. The flow coefficients of flue gas flow in stairwell are obtained by the pressure difference between inside and outside and the velocity of air and flue gas at the opening of stairwell. The values of flow coefficients show that the structure of stairwell has great resistance to flue gas flow in stairwell.
The turbulent mixing motion of flue gas in a vertical channel with closed top was studied. The turbulent mixing motion in a vertical channel was studied without considering wall heat transfer. The turbulent mixing motion equation in a vertical channel with wall heat transfer was established by theoretical analysis. A series of experiments of turbulent mixing motion of thermal buoyancy plume generated by fire source in a closed stairwell were carried out and the experimental data were compared with the numerical results of previous studies and the equations of turbulent mixing motion derived in this paper. The turbulent mixing motion of plume in a vertical stairwell closed at the top is higher than the experimental results.
The location of the neutral surface of a stairwell with multiple openings under fire is studied. The location of the neutral surface of the stairwell with multiple openings is determined by the temperature data, wind speed data and video. Combining with the temperature distribution in the stairwell, the hydrostatic equation, Bernoulli equation and mass conservation equation are used to calculate the fire. The results show that under the same opening condition, the influence of different fire power on the position of the neutral surface of the stairwell is small, and when the fire power is small, the height of the neutral surface of the stairwell will be lower. In the well, the location of the neutral surface of the stairwell is mainly determined by the opening state of the stairwell.
By using a 1:3 scale fire overflow test rig, the shape of the overflow flame outside the burning room under the action of thermal buoyancy of the burning room is studied, the length of the overflow flame in horizontal and vertical directions is analyzed, the coupling relationship between the flame size, the power of the fire source and the opening condition of the burning room is established, and the vibration of the overflow flame is analyzed. The relationship between frequency and room opening condition is studied. The ventilation condition in the fire room under the combined action of external wind and thermal buoyancy of the fire room and the influence of ventilation condition on the combustion in the fire room are studied.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU998.1;TU972.4
本文編號(hào)：2236311
[Abstract]:In recent years, more and more high-rise buildings have been built in China, and with the frequent fire accidents in high-rise buildings, a large number of casualties and property losses have been caused. Statistics show that more than 80% of the deaths in fires are caused by toxic fumes. It is difficult to evacuate people. Vertical passages (elevator shaft, stairwell, pipeline shaft) inside buildings are easy to become important ways of rapid fire spread. The main driving forces of fire smoke in vertical passages of high-rise buildings are chimney effect, turbulent mixing motion, thermal buoyancy, and also vulnerable to the influence of external wind. The motion characteristics of fire smoke in high-rise buildings under dynamic action and the combustion of fire sources in rooms under these forces are of great significance for fire prevention and control of high-rise buildings.
In this paper, the chimney effect, turbulent mixing, thermal buoyancy, external wind and other forces are studied by combining experimental research with theoretical analysis. The corresponding research is carried out by using the 1:3 stairwell test bench with large space and the 1:3 fire overflow test bench.
The rising time of flue gas front in open and closed stairwells was studied. Based on theoretical analysis, the quantitative relationship between the dimensionless rising time of flue gas front and the dimensionless height of stairwells was obtained. The results show that the rising time of flue gas front in open stairwells and closed stairwells is one third of the fire power, respectively. Comparing with the rising time of flue gas in the shaft, it is found that the rising speed of flue gas in the stairwell is slower than that in the shaft. The relationship between dimensionless temperature rise and dimensionless height is analyzed. It is found that the dimensionless temperature rise decreases exponentially with the increase of dimensionless height. The coefficient of attenuation is inversely proportional to the mass flow rate of flue gas in the stairwell. This is verified by experimental data. The flow coefficients of flue gas flow in stairwell are obtained by the pressure difference between inside and outside and the velocity of air and flue gas at the opening of stairwell. The values of flow coefficients show that the structure of stairwell has great resistance to flue gas flow in stairwell.
The turbulent mixing motion of flue gas in a vertical channel with closed top was studied. The turbulent mixing motion in a vertical channel was studied without considering wall heat transfer. The turbulent mixing motion equation in a vertical channel with wall heat transfer was established by theoretical analysis. A series of experiments of turbulent mixing motion of thermal buoyancy plume generated by fire source in a closed stairwell were carried out and the experimental data were compared with the numerical results of previous studies and the equations of turbulent mixing motion derived in this paper. The turbulent mixing motion of plume in a vertical stairwell closed at the top is higher than the experimental results.
The location of the neutral surface of a stairwell with multiple openings under fire is studied. The location of the neutral surface of the stairwell with multiple openings is determined by the temperature data, wind speed data and video. Combining with the temperature distribution in the stairwell, the hydrostatic equation, Bernoulli equation and mass conservation equation are used to calculate the fire. The results show that under the same opening condition, the influence of different fire power on the position of the neutral surface of the stairwell is small, and when the fire power is small, the height of the neutral surface of the stairwell will be lower. In the well, the location of the neutral surface of the stairwell is mainly determined by the opening state of the stairwell.
By using a 1:3 scale fire overflow test rig, the shape of the overflow flame outside the burning room under the action of thermal buoyancy of the burning room is studied, the length of the overflow flame in horizontal and vertical directions is analyzed, the coupling relationship between the flame size, the power of the fire source and the opening condition of the burning room is established, and the vibration of the overflow flame is analyzed. The relationship between frequency and room opening condition is studied. The ventilation condition in the fire room under the combined action of external wind and thermal buoyancy of the fire room and the influence of ventilation condition on the combustion in the fire room are studied.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU998.1;TU972.4
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