Study on the effect of engine operation parameters on cyclic combustion variations and correlation coefficient between the pressure-related parameters of a CNG engine
Study on the effect of engine operation parameters on cyclic combustion variations and correlation coefficient between the pressure-related parameters of a CNG engine
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DOI：
10.1016/j.apenergy.2012.11.043
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发表时间：
2013-04
期刊：
影响因子：
11.2
通讯作者：
Hong Zhang;X. J. Han;B. Yao;G. X. Li
中科院分区：
文献类型：
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作者：
Hong Zhang;X. J. Han;B. Yao;G. X. Li
在稀薄燃烧天然气发动机上进行了天然气燃烧试验，以揭示不同工况下循环燃烧变动（CCV）的规律。研究了发动机工作参数对CCV压力相关特性参数关联式的影响。采用平均指示压力变异系数（COVIMEP）来表征发动机的CCV水平，并采用固定点火正时和最小COVIMEP（MCV）点火正时两种不同的点火正时设定方法进行研究。结果表明，在其它工况参数一定的情况下，COVIMEP最小值出现在最佳点火时刻。在不同的点火提前角下，COVIMEP随当量比、节气门开度和转速的变化趋势有较大的变化，但采用MCV点火提前角法时，COVIMEP随当量比、节气门开度和转速的变化趋势基本不变。通过计算相关系数，发现最大缸压（pmax）与其出现时间（θpmax）、最大缸压上升速率（（dp/dφ）max）之间存在稳定的线性关系。当量比、发动机转速和节气门开度对IMEP与pmax和IMEP与（dp/dφ）max的关系有明显影响。
Natural gas combustion experiments were conducted in a lean burn CNG engine to uncover the regularities of cyclic combustion variations (CCVs) in different operating conditions. The effects of the engine operation parameters on the correlations between pressure related characteristic parameters of CCVs were also investigated. In the study, the level of CCVs was indicated by coefficient of variation of the indicated mean effective pressure (COVIMEP) and the investigation was conducted by two different ignition timing setting methods, which were fixed ignition timing method and the minimum COVIMEP(MCV) ignition timing method. The results show that the minimum COVIMEPappears at the optimal ignition timing while other operation condition parameters were fixed. And the trends of COVIMEPversus equivalent ratio, throttle opening position and engine speed separately vary significantly by setting ignition timing at different fixed value, but the trends were not disturbed as MCV ignition timing method is used. Furthermore, by computing the correlation coefficient, two pairs of parameters, which were the maximum cylinder pressure (pmax) versus its appearance time (θpmax) and pmaxversus the maximum rate of pressure rise ((dp/dφ)max), showed stable and strong linear correlations. However, other two pairs of parameters, which were IMEP versus pmaxand IMEP versus (dp/dφ)max, were influenced obviously by the equivalence ratio, engine speed and throttle opening.