【摘要】：能源、石化產(chǎn)業(yè)的快速興起,使得燃?xì)夤艿辣榧俺鞘懈鱾�(gè)角落；這些管道在給人類(lèi)帶來(lái)便利的同時(shí),也增加了氣體泄漏及火災(zāi)、爆炸事故發(fā)生的危險(xiǎn)性。燃?xì)夤艿酪坏┬孤┎l(fā)生火災(zāi),將會(huì)威脅到周邊的人員安全和造成重大的財(cái)產(chǎn)損失。管道發(fā)生失效泄漏時(shí),會(huì)形成氣體射流；如果在泄漏口處被點(diǎn)火源點(diǎn)燃,則將形成氣體射流火焰；而這些火焰的燃燒基本是在外界通風(fēng)條件下進(jìn)行的,其行為與靜止空氣下的燃燒有較大的差異。因此研究外界風(fēng)作用下氣體射流火燃燒參量的變化,如火焰形態(tài)、火焰脈動(dòng)頻率、輻射強(qiáng)度等,將為火災(zāi)探測(cè)報(bào)警、火災(zāi)撲救提供有力的實(shí)驗(yàn)及理論依據(jù)支持。 因此,本文一方面結(jié)合相關(guān)基礎(chǔ)理論,建立射流擴(kuò)散火焰圖像特征和燃燒特性與外界風(fēng)速、氣體射流出口速度(燃料質(zhì)量流量)間的理論關(guān)系式；另一方面,選取典型燃料丙烷為對(duì)象,以大型燃燒風(fēng)洞為平臺(tái)開(kāi)展一系列實(shí)驗(yàn),研究外界風(fēng)下丙烷湍流擴(kuò)散火焰圖像特征和燃燒特性的變化趨勢(shì)。 火焰圖像特征包括火焰形態(tài)、火焰長(zhǎng)度、火焰傾斜角度與脈動(dòng)頻率。將火焰形態(tài)分為Non-lifted flame和Lifted flame兩大類(lèi)；Non-lifted flame主要依據(jù)射流出口速度和外界風(fēng)速兩者的動(dòng)量通量比進(jìn)行細(xì)分；而Lifted flame的出現(xiàn)條件,與外界風(fēng)速和射流出口速度有關(guān),且射流出口速度起主導(dǎo)作用�；鹧骈L(zhǎng)度與火焰傾斜角度的變化主要由燃料射流出口速度和外界風(fēng)速兩者共同作用的結(jié)果；在所研究的風(fēng)速范圍內(nèi),外界風(fēng)對(duì)火焰具有拉長(zhǎng)作用,風(fēng)速越大,火焰長(zhǎng)度增加,火焰傾斜越明顯,火焰傾斜角度越大。在現(xiàn)有的關(guān)于火焰長(zhǎng)度的模型上,發(fā)展出無(wú)量綱火焰長(zhǎng)度與外界風(fēng)速、射流出口速度之間的關(guān)系；運(yùn)用類(lèi)比思想,通過(guò)引入弗勞德數(shù),定性建立了火焰傾斜角的關(guān)系。外界風(fēng)條件下,橫向風(fēng)速會(huì)對(duì)火焰流場(chǎng)結(jié)構(gòu)產(chǎn)生影響,使得脈動(dòng)現(xiàn)象變得更加復(fù)雜。 從火焰輻射和火焰溫度出發(fā),研究火焰燃燒特性。實(shí)驗(yàn)研究了外界風(fēng)下不同位置處火焰輻射通量的變化；探討了外界風(fēng)下火焰輻射分?jǐn)?shù)測(cè)量模型公式；通過(guò)對(duì)火焰形狀及火焰輻射進(jìn)行相關(guān)假設(shè),結(jié)合前人研究基礎(chǔ),建立了外界風(fēng)速、燃料質(zhì)量流量與火焰輻射分?jǐn)?shù)之間的關(guān)系式,并結(jié)合實(shí)驗(yàn)數(shù)據(jù),發(fā)現(xiàn)其吻合性較好�；鹧鏈囟入S射流速度的增加而呈微小下降趨勢(shì)；在一定外界風(fēng)速范圍內(nèi),外界風(fēng)使得空氣卷吸率增大,但同時(shí)又會(huì)加速流場(chǎng)間的換熱能力,因此使得在外界風(fēng)下,火焰溫度的變化趨勢(shì)變得更加復(fù)雜,其內(nèi)在關(guān)系,仍有待進(jìn)一步深入研究。
[Abstract]:With the rapid development of energy and petrochemical industry, gas pipelines spread all over the city. These pipelines not only bring convenience to human beings, but also increase the risk of gas leakage, fire and explosion accidents. Once the gas pipeline leaks and fires occur, it will threaten the safety of the surrounding personnel and cause significant property losses. When a pipe fails to leak, it forms a gas jet; if it is ignited at the leak by a ignition source, it forms a gas jet flame; and the combustion of these flames is basically carried out under external ventilation. Its behavior is different from that of combustion in stationary air. Therefore, the study of the change of combustion parameters of gas jet under the action of external wind, such as the shape of flame, the frequency of flame pulsation, the intensity of radiation and so on, will provide a strong experimental and theoretical basis for fire detection and alarm and fire suppression. Therefore, on the one hand, based on the relevant basic theory, the theoretical relationship between the characteristics of jet diffusion flame image and combustion characteristics and the velocity of gas jet exit (fuel mass flow) is established; on the other hand, A series of experiments were carried out on the platform of a large combustion wind tunnel with typical fuel propane as an object to study the image characteristics of propane turbulent diffusion flame and the change trend of combustion characteristics in the outside wind. Flame image features include flame shape, flame length, flame tilt angle and pulsation frequency. The flame morphology is divided into two categories, Non-lifted flame and Lifted flame, and Non-lifted flame is subdivided according to the momentum flux ratio of jet exit velocity and external wind speed, while the appearance condition of Lifted flame is related to the external wind speed and jet exit velocity. And jet exit velocity plays a leading role. The variation of flame length and flame inclination angle is mainly caused by the joint action of fuel jet exit velocity and external wind speed. In the range of wind speed studied, the outside wind has the effect of elongating the flame, and the greater the wind speed, the longer the flame length. The greater the inclination of the flame, the greater the angle of the inclination of the flame. Based on the existing model of flame length, the relationship between dimensionless flame length, external wind speed and jet exit velocity is developed, and the relationship of flame inclination angle is qualitatively established by introducing Froude number. Under the external wind condition, the transverse wind speed will affect the flame flow field structure, making the pulsation phenomenon more complicated. Based on the flame radiation and flame temperature, the characteristics of flame combustion are studied. The change of flame radiation flux at different positions under outside wind is studied experimentally. The model formula of flame radiation fraction measurement under external wind is discussed. The relationship between the external wind speed, fuel mass flow rate and flame radiation fraction is established, and the experimental data show that the relationship between the external wind speed, fuel mass flow rate and flame radiation fraction is in good agreement. The flame temperature decreases slightly with the increase of jet velocity. In a certain range of external wind speed, the air entrainment rate increases, but at the same time it accelerates the heat transfer capacity between the flow fields. The variation trend of flame temperature becomes more complex, and its internal relationship still needs to be further 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】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TK16

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本文編號(hào)：2155973