【摘要】：作為在時(shí)間和空間上失去控制的主要危害之一,火災(zāi)帶給人們巨大的經(jīng)濟(jì)損失和人員傷亡。而隧道火災(zāi)由于其獨(dú)特的空間特性,一旦發(fā)生,隧道內(nèi)濃煙密布和遠(yuǎn)離消防大隊(duì)等原因?qū)馂?zāi)撲滅造成很大程度的影響。細(xì)水霧作為近年來(lái)出現(xiàn)的替代性環(huán)保滅火劑,發(fā)展迅速,與其他系統(tǒng)的聯(lián)動(dòng)控制使得細(xì)水霧在能夠在有效時(shí)間內(nèi)抑制火災(zāi)、控制火情的進(jìn)一步蔓延。FLUENT通過(guò)對(duì)火災(zāi)偏微分方程組進(jìn)行數(shù)值求解來(lái)得到火災(zāi)過(guò)程中特性參數(shù)的空間及時(shí)間分布,可以模擬火災(zāi)發(fā)生時(shí)煙氣的溫度及濃度變化過(guò)程,為研究相應(yīng)的消防設(shè)施對(duì)火災(zāi)的抑制提供理論幫助。應(yīng)用FLUENT研究細(xì)水霧的優(yōu)化參數(shù)設(shè)計(jì)及與機(jī)械排煙設(shè)備的聯(lián)動(dòng)控制顯得尤為重要。本文選擇戊烷和庚烷作為火源燃料,采用非預(yù)混燃燒模型,在單室和隧道情況下,研究不同工況下施加細(xì)水霧對(duì)整個(gè)空間內(nèi)溫度和煙氣濃度的變化情況,分析不同細(xì)水霧流量、噴霧方式、霧滴粒徑及排煙方式對(duì)火場(chǎng)內(nèi)溫度場(chǎng)和濃度場(chǎng)產(chǎn)生的影響。(1)借助細(xì)水霧滅單室非正下方火源時(shí)火源遠(yuǎn)端的溫度隨時(shí)間變化的數(shù)據(jù),進(jìn)行對(duì)比驗(yàn)證,證明FLUENT進(jìn)行細(xì)水霧滅火降溫的可靠性,分析誤差原因。在對(duì)比驗(yàn)證模型的基礎(chǔ)上,設(shè)置火源功率為60Kw,改變模擬工況,得出結(jié)論:采用下噴方式,當(dāng)其粒徑為100μm,保證細(xì)水霧流量或流速任一變量恒定,細(xì)水霧流量或流速的增加都會(huì)減少細(xì)水霧對(duì)火災(zāi)的抑制時(shí)間,同比例增加的流量或流速,流速產(chǎn)生的抑制效果要優(yōu)于流量;當(dāng)改變下噴細(xì)水霧粒徑為300μm時(shí),選擇最優(yōu)流量及流速,發(fā)現(xiàn)細(xì)水霧對(duì)火源的抑制效果總體上要低于100μm細(xì)水霧;側(cè)噴方式下,粒徑為100μm,最優(yōu)流量及流速,火源根部受到細(xì)水霧的冷卻效果并不強(qiáng)烈,很難對(duì)整個(gè)火場(chǎng)空間降溫滅火。(2)穩(wěn)態(tài)模擬的公路隧道模型下,分析不同細(xì)水霧霧化錐角對(duì)火場(chǎng)空間的溫度場(chǎng)影響,得出90o時(shí),細(xì)水霧對(duì)整個(gè)火場(chǎng)的控火效果最優(yōu);當(dāng)細(xì)水霧與縱向排煙耦合使用時(shí),排煙與細(xì)水霧的耦合使用可以有效降低火場(chǎng)溫度和排除有毒煙氣,效果要優(yōu)于單獨(dú)施加細(xì)水霧工況,但排煙風(fēng)速會(huì)對(duì)流量較小的細(xì)水霧滅火產(chǎn)生負(fù)面影響。(3)模擬不同機(jī)械排煙工況與細(xì)水霧的耦合作用對(duì)隧道空間溫度場(chǎng)及煙氣濃度產(chǎn)生的影響,結(jié)果表明:頂部排煙耦合細(xì)水霧對(duì)隧道空間的溫度場(chǎng)及煙氣濃度的控制效果要優(yōu)于單獨(dú)施加細(xì)水霧,可以降低煙氣層厚度,但可能會(huì)產(chǎn)生煙氣的倒流及溫度場(chǎng)漩渦。縱向通風(fēng)的效果要優(yōu)于頂部排煙,進(jìn)口端通風(fēng)的送入使得高溫?zé)煔庠谕屏Φ那闆r下向出口端排出,防止煙氣倒流,但會(huì)影響細(xì)水霧霧滴的運(yùn)動(dòng)軌跡及對(duì)火源的抑制效果�？v向通風(fēng)+下游頂部排煙效果最優(yōu),結(jié)合前面兩種排煙工況的優(yōu)點(diǎn),同時(shí)使得隧道空間內(nèi)溫度及煙氣濃度達(dá)到有效控制。
[Abstract]:As one of the main hazards out of control in time and space, fire brings huge economic losses and casualties. Because of its unique spatial characteristics, the tunnel fire has a great influence on the fire extinguishment due to the dense smoke in the tunnel and the distance from the fire-fighting brigade, once the fire occurs, the smoke in the tunnel is dense and far away from the fire-fighting brigade. Water mist, as an alternative environmental extinguishing agent appeared in recent years, has developed rapidly. The linkage control with other systems makes it possible for water mist to suppress fire within an effective time. By numerically solving the partial differential equations of fire, the spatial and temporal distribution of characteristic parameters in the fire process can be obtained, which can simulate the temperature and concentration changes of flue gas during the fire. It provides theoretical help for the study of the fire suppression of the corresponding fire fighting facilities. It is very important to use FLUENT to study the optimization parameter design of water mist and the linkage control with mechanical smoke exhaust equipment. In this paper, pentane and heptane were selected as fire source fuels, and non-premixed combustion model was adopted. Under the condition of single chamber and tunnel, the variation of temperature and smoke concentration under different working conditions were studied, and the different water mist flow rates were analyzed. The effects of spray mode, droplet size and smoke exhaust mode on the temperature field and concentration field in the fire field. (1) the temperature at the far end of the fire source was compared and verified with the help of the data of the temperature at the far end of the fire source with the help of the data of the water mist extinguishing the non-positive lower fire source in one chamber. It is proved that FLUENT is reliable for water mist fire extinguishing and cooling, and the cause of error is analyzed. Based on the comparison and verification of the model, the power of the fire source is set to 60kw, and the simulated working condition is changed. The conclusion is drawn: when the particle size is 100 渭 m, the flow rate or velocity of water mist can be kept constant, and the flow rate of water mist can be kept constant. The increase of water mist flow rate or velocity can reduce the fire suppression time of water mist. The same proportion of the increase in flow rate or velocity, the velocity of flow control effect is better than the flow rate; When the particle size of spray water mist is 300 渭 m, the optimal flow rate and flow rate are selected, and it is found that the effect of water mist on fire suppression is lower than that of 100 渭 m water mist on the whole when the particle size of spray water mist is 300 渭 m. Under the side spraying mode, the particle size is 100 渭 m, the optimal flow rate and velocity, and the cooling effect of water mist on the root of the fire source is not strong, so it is difficult to cool and extinguish the fire space in the whole fire field. (2) under the steady-state simulation of highway tunnel model, the cooling effect is not strong. The influence of different water mist cone angle on the temperature field space is analyzed. The results show that the water mist has the best fire control effect on the whole fire field at 90 o. When the water mist is coupled with the longitudinal exhaust smoke, the coupling use of the water mist and the water mist can effectively reduce the temperature of the fire field and remove the toxic flue gas, and the effect is better than that of applying the water mist alone. But the wind speed of exhaust smoke will have a negative effect on the fire extinguishing of water mist with small flow. (3) simulate the coupling effect of different mechanical smoke exhaust conditions and water mist on the space temperature field and smoke concentration of tunnel. The results show that the control effect of the coupling water mist on the temperature field and smoke concentration of tunnel space is better than that of applying water mist alone, which can reduce the thickness of smoke layer, but it may result in the backward flow and temperature field vortex of flue gas. The effect of longitudinal ventilation is better than that of the top exhaust. The inlet ventilation makes the high temperature flue gas exit to the outlet end under the condition of thrust to prevent the smoke from flowing backwards, but it will affect the trajectory of water mist droplets and the suppression effect of fire source. Longitudinal ventilation has the best exhaust effect on the top of downstream, combining the advantages of the previous two exhaust conditions, and the temperature and smoke concentration in tunnel space can be effectively controlled.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U458

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本文編號(hào)：2441934