本文選題：火溢流 + 腔室火��； 參考：《中國(guó)科學(xué)技術(shù)大學(xué)》2016年博士論文

【摘要】：開(kāi)口火溢流是腔室火中一種常見(jiàn)且極為重要的燃燒現(xiàn)象。通風(fēng)狀況在火溢流的形成及蔓延進(jìn)程中扮演了重要角色。以往研究均主要針對(duì)無(wú)風(fēng)下單開(kāi)口腔室場(chǎng)景,對(duì)其他復(fù)雜無(wú)風(fēng)及有風(fēng)場(chǎng)景則鮮有涉及。本文對(duì)無(wú)風(fēng)下單開(kāi)口及雙開(kāi)口以及側(cè)向風(fēng)作用下的雙開(kāi)口火溢流的形成及燃燒動(dòng)力學(xué)進(jìn)行了系統(tǒng)理論研究,分析了雙開(kāi)口及側(cè)向風(fēng)的影響機(jī)制；采用燃燒風(fēng)洞及小尺度腔室火溢流實(shí)驗(yàn)臺(tái),模擬了不同風(fēng)速下對(duì)稱雙開(kāi)口火溢流場(chǎng)景,對(duì)其燃燒機(jī)理及動(dòng)力學(xué)參數(shù)開(kāi)展了系統(tǒng)研究。研究結(jié)果綜述如下：對(duì)于無(wú)風(fēng)下的單開(kāi)口腔室火溢流場(chǎng)景,燃料供應(yīng)速率及腔室溫度的升高會(huì)造成中性面的降低�；诎敕鍖挼母咚狗植己瘮�(shù)揭示了徑向溫度的軸對(duì)稱高斯自相似分布規(guī)律,實(shí)驗(yàn)數(shù)據(jù)與文獻(xiàn)數(shù)據(jù)較好符合�；谛拚齔ukoski數(shù)和長(zhǎng)度因子揭示了無(wú)風(fēng)下單開(kāi)口火溢流軸向溫度與火焰高度的自相似分布規(guī)律。在連續(xù)火焰區(qū)、間歇火焰區(qū)及浮力羽流區(qū),火溢流的軸向溫度自相似分布函數(shù)具有與經(jīng)典羽流一致的冪指數(shù)。隨著過(guò)余熱釋放速率增加,火溢流逐漸由墻面火向軸對(duì)稱火焰轉(zhuǎn)變,在墻面火焰區(qū)火焰高度自相似分布函數(shù)的冪指數(shù)與經(jīng)典羽流不同,壁面附近空氣卷吸受限可能是主要原因。無(wú)風(fēng)條件下,相比于單開(kāi)口情形,雙開(kāi)口的存在會(huì)使腔室的中性面升高,并對(duì)腔室火溫度產(chǎn)生影響�；诶碚撏茖�(dǎo)獲得了無(wú)風(fēng)下非對(duì)稱雙開(kāi)口火溢流的中性面高度模型,與文獻(xiàn)中數(shù)據(jù)符合較好。側(cè)向風(fēng)的加入,會(huì)因補(bǔ)充氧氣促進(jìn)燃燒,也可冷卻可燃物,這兩種效應(yīng)會(huì)相互競(jìng)爭(zhēng),從而對(duì)腔室燃燒強(qiáng)度和室內(nèi)溫度產(chǎn)生影響。理論推導(dǎo)表明,側(cè)向風(fēng)對(duì)對(duì)稱雙開(kāi)口的腔室火溢流壓差分布產(chǎn)生三種影響,即直接在順風(fēng)及逆風(fēng)沿的腔室開(kāi)口施加風(fēng)壓：造成靜壓變化：造成流體靜壓變化。側(cè)向風(fēng)的作用還會(huì)造成小尺度對(duì)稱雙開(kāi)口腔室火溢流順風(fēng)沿和逆風(fēng)沿中性面升高及降低,并影響火溢流的流態(tài)及流動(dòng)方向。以上推導(dǎo)的結(jié)論均與實(shí)驗(yàn)數(shù)據(jù)一致。不同側(cè)向風(fēng)風(fēng)速下的實(shí)驗(yàn)數(shù)據(jù)表明,采用半峰寬(FWHM)作為歸一化變量的無(wú)量綱高斯函數(shù)可以較好地?cái)M合不同風(fēng)速下的徑向溫度數(shù)據(jù),不會(huì)因不同風(fēng)速造成的軸線軌跡彎曲而變化。側(cè)向風(fēng)作用會(huì)使火溢流軸線軌跡形成初始階段的脫離壁面區(qū)域和隨后的附著壁面區(qū)域：半峰寬(FWHM)沿高度方向上呈弱線性分布。側(cè)向風(fēng)風(fēng)速1.5 m/s及3 m/s的實(shí)驗(yàn)數(shù)據(jù)表明,耦合側(cè)向風(fēng)的無(wú)量綱模型及長(zhǎng)度因子可以較好地對(duì)不同側(cè)向風(fēng)風(fēng)速、開(kāi)口尺寸和內(nèi)部燃燒強(qiáng)度下的火溢流軸向溫度及壁面總熱通量進(jìn)行擬合。在連續(xù)火焰區(qū)、間歇火焰區(qū)及浮力羽流區(qū),火溢流軸向溫度自相似分布函數(shù)具有與經(jīng)典羽流一致的冪指數(shù)：風(fēng)速增加會(huì)使得二個(gè)火焰分區(qū)之間的轉(zhuǎn)化加快,空氣卷吸增強(qiáng)是主要原因。側(cè)向風(fēng)作用造成的中性面高度下降會(huì)增強(qiáng)火溢流的近場(chǎng)及遠(yuǎn)場(chǎng)空氣卷吸；外立面的空氣卷吸受限也會(huì)對(duì)火溢流的溫度分布及軸線軌跡產(chǎn)生顯著的影響。不同風(fēng)速下的數(shù)據(jù)表明,側(cè)向風(fēng)的作用會(huì)對(duì)壁面總熱通量及溫度產(chǎn)生兩個(gè)相互競(jìng)爭(zhēng)的作用,使其隨著風(fēng)速增加出現(xiàn)非線性變化趨勢(shì)。
[Abstract]:Open fire overflow is a common and extremely important combustion phenomenon in the chamber fire. Ventilation has played an important role in the formation and spread of the fire overflow. Previous studies were mainly aimed at the single opening of the oral chamber scene without wind, and rarely involved in other complicated and windless scenes. The formation of double opening fire overflow and combustion dynamics under side wind are systematically studied, and the influence mechanism of double opening and lateral wind is analyzed. The flow field of symmetrical double opening under different wind speeds is simulated by combustion wind tunnel and small scale chamber fire overflow test platform, and its combustion mechanism and dynamic parameters are carried out. The research results are summarized as follows: for a single open oral chamber fire overflow scene without wind, the fuel supply rate and the increase of the chamber temperature will result in the reduction of the neutral surface. The Gauss distribution function based on the half peak width reveals the axisymmetric Gauss self similarity distribution of the radial temperature, and the experimental data are in good agreement with the literature data. Based on the modified Zukoski number and the length factor, the self similar distribution of the axial temperature and the flame height of a single open fire overflow is revealed. In the continuous flame region, the intermittent flame region and the buoyancy plume, the self similar distribution function of the axial temperature of the fire overflow has the power exponent consistent with the classical plume. With the increase of the rate of excess heat release, The fire overflow gradually changes from the wall fire to the axisymmetric flame. The power exponent of the self similar distribution function of the flame height in the wall flame area is different from that of the classical plume. The air entrainment near the wall may be the main reason. Under the condition of no wind, the double opening will increase the neutral surface of the chamber and the chamber fire temperature. Based on the theoretical deduction, the neutral surface height model of unsymmetrical double opening fire overflow is obtained, which is in good agreement with the data in the literature. The addition of the side wind will increase the combustion and can cool the combustibles. These two effects will compete with each other, thus influencing the chamber combustion strength and indoor temperature. The derivation shows that the lateral wind has three effects on the distribution of the pressure difference distribution in the chamber with symmetrical double opening, that is, the wind pressure is applied directly to the opening of the chamber with the wind and the opposite wind, which causes the static pressure change: the hydrostatic pressure changes. The lateral wind will also cause the small scale symmetrical double opening chamber fire overflow along the wind and the counter wind to rise along the neutral surface. The above conclusions are all consistent with the experimental data. The experimental data under different lateral wind speeds show that the dimensionless Gauss function using half peak width (FWHM) as a normalized variable can well fit the radial temperature data under different wind speeds and will not be caused by different wind speeds. The axis trajectory of the axis changes. The lateral wind can cause the fire overflow axis to form the initial stage of the separation from the wall area and the subsequent attachment wall area: the half peak width (FWHM) is a weak linear distribution along the direction of height. The experimental data of 1.5 m/s and 3 m/s for the lateral wind wind speed show that the dimensionless model and length factor of the wind in the coupling side In the continuous flame region, the intermittent flame area and the buoyancy plume region, the self similar distribution function of the fire overflow axial temperature is consistent with the classical plume in the continuous flame region, the intermittent flame area and the buoyancy plume region. The increase of wind speed will make the wind speed increase two. The main reason for the conversion between the flame zones is that the air entrainment is the main reason. The decrease of the neutral surface caused by the lateral wind effect will enhance the near and far field air entrainment of the fire overflow; the air entrainment limitation of the outer surface will also have a significant effect on the temperature distribution and axis trajectory of the fire overflow. The effect of wind on the total heat flux and temperature of the wall has two competing effects, making it nonlinear trend with the increase of wind speed.

【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】：2016
【分類號(hào)】：X932

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