In this paper,the characteristics of detonation combustion ignited by AC-driven non-thermal plasma and spark plug in air/acetylene mixture have been compared in a doubletube experiment system.The two tubes had the sam...In this paper,the characteristics of detonation combustion ignited by AC-driven non-thermal plasma and spark plug in air/acetylene mixture have been compared in a doubletube experiment system.The two tubes had the same structure,and their closed ends were installed with a plasma generator and a spark plug,respectively.The propagation characteristics of the flame were measured by pressure sensors and ion probes.The experiment results show that,compared with a spark plug,the non-thermal plasma obviously broadened the range of equivalence ratio when the detonation wave could develop successfully,it also heightened the pressure value of detonation wave.Meanwhile,the detonation wave development time and the entire flame propagation time were reduced by half.All of these advantages benefited from the larger ignition volume when a non-thermal plasma was applied.展开更多
Gasoline compression combustion engine has the advantages of low emission and high efficiency,which is very promising for research,but it is difficult to apply under low-load conditions.Gasoline has the characteristic...Gasoline compression combustion engine has the advantages of low emission and high efficiency,which is very promising for research,but it is difficult to apply under low-load conditions.Gasoline has the characteristics of low reactivity;in the case of low thermodynamic state in the cylinder,the fire delay period of the fuel is longer,and the combustion phase is relatively lagging,which will lead to the increase of combustion cycle fluctuations,and even difficult to ignite and other adverse combustion phenomena.In order to improve the combustion stability of Gasoline Compression Ignition(GCI)engine under low-load condition and expand the limit of low-load combustion boundary,gasoline was reformed without catalyst under the boundary condition of reforming temperature of 488 K and reforming equivalent ratio of 8,and the concentration of reformed product was measured by a gas detection device.Subsequently,the coupling of the reformed product and spark plug with GCI engine under low-load condition was investigated to analyze the effect on engine combustion and emission.The results showed that the initial combustion timing of the low-load GCI engine was late,but the addition of reformed products could advance the combustion phase,shorten the combustion duration,reduce single-cycle NOx emission,and improve the small-load operation characteristics of GCI engine.Coupled spark plug ignition on the basis of adding reformed products could further improve the problem of combustion stability under low-load GCI engine.And the optimization effect became more obvious as the ignition position of the spark plug moves down.However,spark plug ignition would cause local high temperature areas,resulting in an increase in NOx,emission.展开更多
The ceramic insulators of spark plugs in gasoline engines are especially prone to damage when deto-knock occurs.To under-stand the damage process and mechanism,the present work investigated the impact resistance of ce...The ceramic insulators of spark plugs in gasoline engines are especially prone to damage when deto-knock occurs.To under-stand the damage process and mechanism,the present work investigated the impact resistance of ceramic insulators using detonation waves as impact sources.A test device that generates detonation waves was developed,representing a novel means of evaluating the knock resistance of ceramic insulators.Various impact types and detonation intensities were employed,and detonation initiation and propagation at peak pressures greater than 100 MPa were assessed using synchronous high-speed direct photography and pressure measurements.The test results demonstrate that ceramic insulators tend to break at the base of the breathing chamber when damaged by a single high peak pressure detonation wave impact.In contrast,multiple low pressure impacts eventually break the insulator into multiple fragments.The data also show that the positioning of a ground electrode upstream of the ceramic insulator greatly increases the resistance of the ceramic to the detonation impact.A two-dimensional computational fluid dynamics simulation coupled with a chemical kinetics analysis demonstrated that this improved resistance can be ascribed to a reduced peak pressure that appears after the detonation wave diffracts from the electrode prior to contacting the ceramic insulator.展开更多
The establishment of Nanjing Electroceramics Factory in 1953 marks the inauguration of spark plug production in China. China now has built an independent system of spark plug sector with 12 enterprises, a research ins...The establishment of Nanjing Electroceramics Factory in 1953 marks the inauguration of spark plug production in China. China now has built an independent system of spark plug sector with 12 enterprises, a research institute (Nanjing Spark Plug Research Institute), a testing center in charge of products supervision (Center for展开更多
早燃是缸内增压直喷汽油机(TGDI)的常见现象和严重问题。为了研究火花塞是否为导致早燃的热点,利用一台1.5 L TGDI发动机在1500~5800 r/min全负荷和部分负荷下,试验研究了火花塞中心电极和4个不同方向的侧电极温度,并进行了早燃检查。...早燃是缸内增压直喷汽油机(TGDI)的常见现象和严重问题。为了研究火花塞是否为导致早燃的热点,利用一台1.5 L TGDI发动机在1500~5800 r/min全负荷和部分负荷下,试验研究了火花塞中心电极和4个不同方向的侧电极温度,并进行了早燃检查。试验结果表明,在发动机全负荷下,火花塞中心电极和侧电极温度均随转速增加而逐渐升高,但在2500 r/min后因空燃比加浓导致火花塞温度变化不明显。在发动机转速2000、3500和5800 r/min部分负荷下,火花塞中心电极和侧电极温度随负荷增大先升高后降低,在中等负荷时的温度最高。在定向火花塞侧电极4个方向中12点钟方向侧电极的温度最高,比3~9点温度分别高出了34、45和10℃,而6点钟方向温度最低。研究结果表明TGDI发动机部分负荷时,侧电极安装于12点钟方向时火花塞温度最高,合理的结构设计和控制参数设置可以避免早燃的发生。展开更多
基金supported by National Natural Science Foundation of China(No.51176001)
文摘In this paper,the characteristics of detonation combustion ignited by AC-driven non-thermal plasma and spark plug in air/acetylene mixture have been compared in a doubletube experiment system.The two tubes had the same structure,and their closed ends were installed with a plasma generator and a spark plug,respectively.The propagation characteristics of the flame were measured by pressure sensors and ion probes.The experiment results show that,compared with a spark plug,the non-thermal plasma obviously broadened the range of equivalence ratio when the detonation wave could develop successfully,it also heightened the pressure value of detonation wave.Meanwhile,the detonation wave development time and the entire flame propagation time were reduced by half.All of these advantages benefited from the larger ignition volume when a non-thermal plasma was applied.
基金supported by the National Natural Science Foundation of China(NO.52006043).
文摘Gasoline compression combustion engine has the advantages of low emission and high efficiency,which is very promising for research,but it is difficult to apply under low-load conditions.Gasoline has the characteristics of low reactivity;in the case of low thermodynamic state in the cylinder,the fire delay period of the fuel is longer,and the combustion phase is relatively lagging,which will lead to the increase of combustion cycle fluctuations,and even difficult to ignite and other adverse combustion phenomena.In order to improve the combustion stability of Gasoline Compression Ignition(GCI)engine under low-load condition and expand the limit of low-load combustion boundary,gasoline was reformed without catalyst under the boundary condition of reforming temperature of 488 K and reforming equivalent ratio of 8,and the concentration of reformed product was measured by a gas detection device.Subsequently,the coupling of the reformed product and spark plug with GCI engine under low-load condition was investigated to analyze the effect on engine combustion and emission.The results showed that the initial combustion timing of the low-load GCI engine was late,but the addition of reformed products could advance the combustion phase,shorten the combustion duration,reduce single-cycle NOx emission,and improve the small-load operation characteristics of GCI engine.Coupled spark plug ignition on the basis of adding reformed products could further improve the problem of combustion stability under low-load GCI engine.And the optimization effect became more obvious as the ignition position of the spark plug moves down.However,spark plug ignition would cause local high temperature areas,resulting in an increase in NOx,emission.
基金This work was supported by National Natural Science Foundation of China(Grant Nos.91541206 and 51706121)China Postdoctoral Science Foundation(Grant No.2017T100076).
文摘The ceramic insulators of spark plugs in gasoline engines are especially prone to damage when deto-knock occurs.To under-stand the damage process and mechanism,the present work investigated the impact resistance of ceramic insulators using detonation waves as impact sources.A test device that generates detonation waves was developed,representing a novel means of evaluating the knock resistance of ceramic insulators.Various impact types and detonation intensities were employed,and detonation initiation and propagation at peak pressures greater than 100 MPa were assessed using synchronous high-speed direct photography and pressure measurements.The test results demonstrate that ceramic insulators tend to break at the base of the breathing chamber when damaged by a single high peak pressure detonation wave impact.In contrast,multiple low pressure impacts eventually break the insulator into multiple fragments.The data also show that the positioning of a ground electrode upstream of the ceramic insulator greatly increases the resistance of the ceramic to the detonation impact.A two-dimensional computational fluid dynamics simulation coupled with a chemical kinetics analysis demonstrated that this improved resistance can be ascribed to a reduced peak pressure that appears after the detonation wave diffracts from the electrode prior to contacting the ceramic insulator.
文摘The establishment of Nanjing Electroceramics Factory in 1953 marks the inauguration of spark plug production in China. China now has built an independent system of spark plug sector with 12 enterprises, a research institute (Nanjing Spark Plug Research Institute), a testing center in charge of products supervision (Center for
