本文關(guān)鍵詞：CNG公交車立交橋下停車場泄漏擴散仿真研究　出處：《首都經(jīng)濟貿(mào)易大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： CNG公交車 停車場 泄漏擴散 數(shù)值模擬

【摘要】：隨著人類的進(jìn)步與發(fā)展,天然氣逐步成為城市能源的重要組成部分。作為以壓縮天然氣為燃料的CNG (Compressed Natural Gas)公交車也被大量投入使用,其供氣工藝十分復(fù)雜,導(dǎo)致泄漏的點源較多,一旦發(fā)生泄漏將會對周圍人員和財產(chǎn)安全造成威脅。與此同時,城市立交橋作為現(xiàn)代都市的產(chǎn)物應(yīng)運而生,其橋下空間被大量使用作為停車場所,也包括大量CNG公交車的停放。天然氣的密度比空氣小,CNG公交車在立交橋下發(fā)生泄漏后將會造成天然氣的積聚,并形成爆炸性環(huán)境。因此,對CNG公交車在立交橋下停車場發(fā)生泄漏擴散的情況進(jìn)行研究和仿真模擬具有重要意義。本文首先對氣體的擴散機理和過程進(jìn)行了分析,了解到氣體的擴散是一個繁復(fù)的過程。氣體擴散是因為受到動力因素和熱力因素的影響,其擴散過程一般分為三個步驟：介質(zhì)的泄漏,流體氣云的形成,氣云的擴散。其次,基于國內(nèi)外學(xué)者的研究成果,提出了影響氣體擴散的主要因素,包括泄漏源、泄漏介質(zhì)密度、地面條件和氣象條件等。然后,以北京市新興橋、遠(yuǎn)通橋、大北窯橋三種不同結(jié)構(gòu)的立交橋為原型,采用Gambit軟件建立了相應(yīng)的幾何模型,并進(jìn)行了網(wǎng)格劃分。最后,將網(wǎng)格文件導(dǎo)入Fluent進(jìn)行了模擬計算,并分別討論了風(fēng)速、橋體結(jié)構(gòu)、泄漏速率的影響下天然氣質(zhì)量濃度分布情況及爆炸區(qū)域的變化規(guī)律。對比得到的濃度分布云圖可以看出,其他條件相同,當(dāng)風(fēng)速為4m/s時,兩車之間會發(fā)生天然氣的大量積聚,爆炸區(qū)域會比較大；對比三種立交橋下的泄漏擴散情況時,大北窯橋發(fā)生天然氣泄漏時更容易形成大片的爆炸區(qū)域,遠(yuǎn)通橋更容易造成天然氣較高濃度的積聚；當(dāng)泄漏速率為20m/s時,橋下爆炸區(qū)域的分布范圍相比較30m/s、40m/s、50m/s時更廣。通過得到的濃度分布云圖、爆炸區(qū)域分布圖,以及不同時間橋下特殊點的濃度變化情況,可為立交橋下停車場的安全管理工作提出一定的指導(dǎo)建議,也可以為事故預(yù)警和事故分析等提供重要的依據(jù)。
[Abstract]:With the progress and development of mankind. Natural gas has gradually become an important part of urban energy. As a compressed Natural gas based on compressed natural gas (CNG). Buses are also used in large numbers. The gas supply technology is very complex, resulting in a large number of leakage point sources, once the leakage will pose a threat to the safety of people and property around. At the same time, the city overpass as a product of the modern city came into being. The space under the bridge is used as a parking place, including the parking of a large number of CNG buses. The density of natural gas is smaller than that of the air, which will cause the accumulation of natural gas after the leakage of the bus under the overpass. And create an explosive environment. It is of great significance to study and simulate the leakage and diffusion of CNG bus in the parking lot under the overpass. Firstly, the mechanism and process of gas diffusion are analyzed in this paper. It is understood that gas diffusion is a complicated process. Gas diffusion is affected by dynamic and thermodynamic factors. The diffusion process is generally divided into three steps: the leakage of medium and the formation of fluid gas cloud. Secondly, based on the research results of domestic and foreign scholars, the main factors affecting gas diffusion, including leakage source, leakage medium density, surface conditions and meteorological conditions, are put forward. Based on Beijing Xinxing Bridge, Yuantong Bridge and Dabei Kiln Bridge, the corresponding geometric model is established by using Gambit software. Finally, the mesh is divided. The grid file is imported into Fluent for simulation calculation, and the wind speed and bridge structure are discussed respectively. Under the influence of the leakage rate, the gas mass concentration distribution and the variation law of the explosion region are obtained. The comparison of the cloud diagram of the concentration distribution shows that the other conditions are the same, when the wind speed is 4 m / s. There will be a large accumulation of natural gas between the two vehicles, and the explosion area will be larger; Compared with the leakage and diffusion situation under the three kinds of overpass bridge, it is easier to form a large explosion area when the natural gas leak occurs in the Dabei kiln bridge, and the remote bridge is more likely to cause the accumulation of higher concentration of natural gas. When the leakage rate is 20 m / s, the distribution of the explosion area under the bridge is wider than that at 30 m / s, 40 m / s, 50 m / s. The variation of the concentration of special points under the bridge at different times can provide some guidance for the safety management of the parking lot under the overpass, as well as provide important basis for accident warning and accident analysis.
【學(xué)位授予單位】：首都經(jīng)濟貿(mào)易大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：U492.8
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本文編號：1408470