【摘要】：隨著人們對環(huán)境保護意識的增強以及國家針對機動車排放相關法律法規(guī)的完善,直噴式柴油機較高的顆粒物排放成為限制柴油機發(fā)展的重要因素,這也成為許多學者重點研究的課題。最近的研究表明,直噴式柴油機噴霧燃燒時的空氣卷吸率對碳煙的形成具有重要影響。而直噴柴油機的火焰浮起長度(Flame Lift-Off Length)以及噴霧錐角等能夠通過影響油氣混合進而影響到空氣卷吸率。本文設計改進了定容燃燒彈系統(tǒng)實驗設備以適應對燃油噴霧燃燒特性參數(shù)的測量。通過改進后的燃燒彈系統(tǒng)對柴油火焰浮起長度進行測量。并利用溫度、壓力等傳感器測量實時溫度、壓力等變化值。在此基礎上研究了定容燃燒彈內(nèi)的環(huán)境溫度、環(huán)境密度、環(huán)境壓力以及噴油壓力等參數(shù)對火焰浮起長度的影響。對比國內(nèi)外研究成果,從而估算了空氣卷吸率隨這些參數(shù)的變化規(guī)律,進而分析了燃燒參數(shù)對碳煙(soot)生成的影響。實驗結果發(fā)現(xiàn),在穩(wěn)態(tài)條件下,也就是在體積無變化的燃燒彈內(nèi),初始環(huán)境的溫度、壓力以及密度的增加會減小火焰浮起長度,從而降低空氣卷吸率,其中火焰浮起長度對實驗條件下的環(huán)境溫度敏感度要大于環(huán)境壓力,火焰浮起長度相對于環(huán)境溫度和密度的變化為非線性的;火焰浮起長度隨噴射壓力的增加而增加。在定性分析了火焰浮起長度的變化趨勢的基礎上進行了定量分析,利用1stOpt軟件的曲線擬合和參數(shù)優(yōu)化功能得到了在穩(wěn)態(tài)條件下柴油噴霧燃燒火焰浮起長度的經(jīng)驗公式。從而得出燃燒室溫度、壓力以及噴油壓力等參數(shù)對柴油在噴霧燃燒中的空氣卷吸率以及碳煙生成的影響。進而利用煤油作為對比燃油進行了同樣的實驗分析,得出了其火焰浮起長度大小以及變化趨勢并繪制了兩種燃油對比分析圖。在兩者的對比分析圖中,將兩種燃油浮起長度相同時呈現(xiàn)的曲線稱之為等高線現(xiàn)象。通過等高線位置的移動得出兩者變化趨勢的不同。根據(jù)兩者烴族組分的不同進行了分析,解釋了其合理性并預測了不同含碳原子量的燃油浮起長度變化趨勢。本文對火焰浮起長度的研究有助于未來在柴油機研發(fā)中,通過改善燃燒室參數(shù)改變浮起長度以及空氣卷吸率,從而盡可能控制碳煙的生成,進一步降低排放。
[Abstract]:With the improvement of the awareness of environmental protection and the improvement of the national laws and regulations on the emission of motor vehicles, the high particulate emission of the direct injection diesel engine has become an important factor to limit the development of the diesel engine, which has also become the subject of the key research of many scholars. Recent studies have shown that the rate of air entrainment in the spray combustion of a direct injection diesel engine has an important effect on the formation of soot. The flame lift-off length and the spray cone angle of the direct injection diesel engine can affect the air volume suction rate through the influence of oil and gas mixing. In this paper, the experimental equipment of the constant-volume combustion bomb system is designed to adapt to the measurement of the fuel spray combustion characteristic parameters. And measuring the floating length of the diesel flame by the improved combustion bomb system. And the changes of the real-time temperature, the pressure and the like are measured by means of sensors such as temperature, pressure and the like. On this basis, the influence of the parameters such as the ambient temperature, the environmental density, the ambient pressure and the injection pressure on the floating length of the flame was studied. The effect of the combustion parameters on the soot formation is also analyzed by comparing the research results at home and abroad. the experimental results show that the temperature, pressure and density of the initial environment can reduce the flame floating length under the steady-state condition, that is, in the volume-free combustion bomb, so that the air volume suction rate is reduced, The sensitivity of the flame floating length to the ambient temperature under the experimental conditions is higher than the ambient pressure, and the variation of the flame floating length with respect to the ambient temperature and the density is non-linear; the flame floating length is increased with the increase of the injection pressure. On the basis of the qualitative analysis of the variation trend of the flame floating length, the empirical formula of the floating length of the diesel fuel spray combustion flame under the steady-state condition is obtained by using the curve fitting and the parameter optimization function of the 1stOt software. So as to obtain the influence of the parameters of the temperature, the pressure and the injection pressure of the combustion chamber on the air volume absorption rate and the soot formation of the diesel in the spray combustion. In the same way, kerosene is used as the comparative fuel to carry on the same experimental analysis, the length and the variation trend of the flame floating length are obtained, and the two fuel-fuel contrast analysis graphs are drawn. In the comparative analysis of the two, the curves presented when the two fuel float lengths are the same are called contour phenomena. The movement of the contour position results in a difference in the changing trend of the two. Based on the analysis of the different hydrocarbon group components, the rationality and the prediction of the variation trend of the fuel floating length of different carbon-containing atoms are explained. In this paper, the study of the length of the flame is helpful to the future in the development of the diesel engine, and the floating length and the air volume absorption rate can be changed by improving the parameters of the combustion chamber, so as to control the generation of the soot as much as possible and further reduce the emission.
【學位授予單位】：重慶交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TK421.2

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本文編號：2511688