预燃室射流点火装置的设计与性能研究
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摘要
为改善天然气发动机燃烧特性,设计了用于射流点火的内置式半球型四孔预燃室,利用全燃烧场可视的快速压缩机(RCM),采用同步压力传感器和高速摄影机进行了点火燃烧试验研究,并与传统火花点火对比分析。结果表明,采用本文设计的预燃室射流点火装置能达到强化点火、加速燃烧的明显效果。相比于传统火花点火,预燃室式射流点火的滞燃期和燃烧持续期缩短,最高燃烧压力和最大累计放热量提高,且随着负荷的增大,性能改善幅度增加。在大负荷工况下,滞燃期和燃烧持续期均约缩短了55%,最高燃烧压力和最大累计放热量分别提高7%和10%。此外,预燃室式射流点火方式的点火和燃烧稳定性优于传统火花点火,滞燃期和最高燃烧压力波动极小。高速摄影的结果表明,预燃室式射流点火在主燃室内快速产生沿喷孔方向高速发展的射流火焰,引发迅速燃烧,而传统火花点火呈现火焰缓慢传播燃烧形态。
In order to improve the combustion characteristics of natural gas engine,a built-in hemispherical pre-combustion chamber with four orifices for jet ignition is designed and experimentally investigated into its ignition and combustion on a rapid compression machine with full combustion field visibility by using synchronous pressure sensor and high-speed camera,and is compared with traditional spark ignition. The results show that the pre-combustion chamber jet igniter designed can achieve significant effects in intensifying ignition and accelerating combustion. Compared with traditional spark ignition,the delay burning period and combustion duration of pre-combustion chamber jet ignition shorten and the maximum combustion pressure and accumulated heat release increase,with the extent of these improvements rising with the increase of load. Under high load conditions,the degrees of rises in both delay burning period and combustion duration reach 55%,while those in maximum combustion pressure and accumulated heat release are 7% and 10% respectively. In addition,the ignition and combustion in pre-combustion chamber jet ignition are more stable than those in traditional spark ignition,with little fluctuation in delay burning period and maximum combustion pressure. The results of high-speed photography show that with pre-combustion chamber jet igniter,the jet flame is generated in main combustion chamber and rapidly develops along the directions of pre-chamber orifices' axes,triggering swift combustion,while a combustion pattern with slow flame propagation is exhibited in traditional spark ignition.
In order to improve the combustion characteristics of natural gas engine,a built-in hemispherical pre-combustion chamber with four orifices for jet ignition is designed and experimentally investigated into its ignition and combustion on a rapid compression machine with full combustion field visibility by using synchronous pressure sensor and high-speed camera,and is compared with traditional spark ignition. The results show that the pre-combustion chamber jet igniter designed can achieve significant effects in intensifying ignition and accelerating combustion. Compared with traditional spark ignition,the delay burning period and combustion duration of pre-combustion chamber jet ignition shorten and the maximum combustion pressure and accumulated heat release increase,with the extent of these improvements rising with the increase of load. Under high load conditions,the degrees of rises in both delay burning period and combustion duration reach 55%,while those in maximum combustion pressure and accumulated heat release are 7% and 10% respectively. In addition,the ignition and combustion in pre-combustion chamber jet ignition are more stable than those in traditional spark ignition,with little fluctuation in delay burning period and maximum combustion pressure. The results of high-speed photography show that with pre-combustion chamber jet igniter,the jet flame is generated in main combustion chamber and rapidly develops along the directions of pre-chamber orifices' axes,triggering swift combustion,while a combustion pattern with slow flame propagation is exhibited in traditional spark ignition.
引文
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[4]SHAH A,TUNESTAL P,JOHANSSON B,et al.Investigation of performance and emission characteristics of a heavy duty natural gas engine operated with pre-chamber spark plug and dilution with excess air and EGR[C].SAE Paper 2012-01-1980.
[5]TAKASHIMA Y,TANAKA H,SAKO T,et al.Evaluation of engine performance and combustion in natural gas engine with prechamber plug under lean burn conditions[C].SAE Paper 2014-32-0103.
[6]ATTARD W P,BLAXILL H,ANDERSON E K,et al.Knock limit extension with a gasoline fueled pre-chamber jet igniter in a modern vehicle powertrain[C].SAE Paper 2012-01-1143.
[7]ANDERSON E K,ATTARD W P,BROWN A,et al.Experimental study of a pre-chamber jet igniter in a turbocharged Rotax 914aircraft engine[C].SAE Paper 2013-01-1629.
[8]SHAH A,TUNESTAL P,JOHANSSON B.Effect of pre-chamber volume and nozzle diameter on pre-chamber ignition in heavy duty natural gas engines[C].SAE Paper 2015-01-0867.
[9]DI H,HE X,ZHANG P,et al.Effects of buffer gas composition on low temperature ignition of iso-octane and n-heptane[J].Combustion&Flame,2014,161(10):2531-2538.
[10]KORAKIANITIS T,NAMASIVAYAM A M,CROOKES R J.Natural-gas fueled spark-ignition(SI)and compression-ignition(CI)engine performance and emissions[J].Progress in Energy&Combustion Science,2011,37(1):89-112.
[11]WANG Z,HUANG J,WANG Q,et al.Experimental study of microwave resonance plasma ignition of methane-air mixture in a constant volume cylinder[J].Combustion&Flame,2015,162(6):2561-2568.
[12]EVANS R L,BLASZCZYK J.A comparative study of the performance and exhaust emissions of a spark ignition engine fuelled by natural gas and gasoline[J].Proceedings of the Institution of Mechanical Engineers Part D:Journal of Automobile Engineering,1997,211(1):39-47.
[13]王建昕,帅石金.汽车发动机原理[M].1版.北京:清华大学出版社,2011:228-231.
[2]DAS A,WATSON H C.Development of a natural gas spark ignition engine for optimum performance[J].Proceedings of the Institution of Mechanical Engineers Part D:Journal of Automobile Engineering,1997,211(5):361-378.
[3]TOULSON E,SCHOCK H J,ATTARD W P.A review of prechamber initiated jet ignition combustion systems[C].SAE Paper2010-01-2263.
[4]SHAH A,TUNESTAL P,JOHANSSON B,et al.Investigation of performance and emission characteristics of a heavy duty natural gas engine operated with pre-chamber spark plug and dilution with excess air and EGR[C].SAE Paper 2012-01-1980.
[5]TAKASHIMA Y,TANAKA H,SAKO T,et al.Evaluation of engine performance and combustion in natural gas engine with prechamber plug under lean burn conditions[C].SAE Paper 2014-32-0103.
[6]ATTARD W P,BLAXILL H,ANDERSON E K,et al.Knock limit extension with a gasoline fueled pre-chamber jet igniter in a modern vehicle powertrain[C].SAE Paper 2012-01-1143.
[7]ANDERSON E K,ATTARD W P,BROWN A,et al.Experimental study of a pre-chamber jet igniter in a turbocharged Rotax 914aircraft engine[C].SAE Paper 2013-01-1629.
[8]SHAH A,TUNESTAL P,JOHANSSON B.Effect of pre-chamber volume and nozzle diameter on pre-chamber ignition in heavy duty natural gas engines[C].SAE Paper 2015-01-0867.
[9]DI H,HE X,ZHANG P,et al.Effects of buffer gas composition on low temperature ignition of iso-octane and n-heptane[J].Combustion&Flame,2014,161(10):2531-2538.
[10]KORAKIANITIS T,NAMASIVAYAM A M,CROOKES R J.Natural-gas fueled spark-ignition(SI)and compression-ignition(CI)engine performance and emissions[J].Progress in Energy&Combustion Science,2011,37(1):89-112.
[11]WANG Z,HUANG J,WANG Q,et al.Experimental study of microwave resonance plasma ignition of methane-air mixture in a constant volume cylinder[J].Combustion&Flame,2015,162(6):2561-2568.
[12]EVANS R L,BLASZCZYK J.A comparative study of the performance and exhaust emissions of a spark ignition engine fuelled by natural gas and gasoline[J].Proceedings of the Institution of Mechanical Engineers Part D:Journal of Automobile Engineering,1997,211(1):39-47.
[13]王建昕,帅石金.汽车发动机原理[M].1版.北京:清华大学出版社,2011:228-231.