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
In this study,a triple spark ignition scheme was first designed on a three-cylinder 1.5-L dedicated hybrid engine(DHE).On this basis,the effect of different ignition modes on engine combustion and emission characteris...In this study,a triple spark ignition scheme was first designed on a three-cylinder 1.5-L dedicated hybrid engine(DHE).On this basis,the effect of different ignition modes on engine combustion and emission characteristics was studied,especially under high dilution condition.The results tested at 2000 r/min and 0.8 MPa BMEP(brake mean effective pressure)show that with highly increased in-cylinder flow intensity,using only passive prechamber(PPC)has a lower lean limit than that with single central spark plug(CSP),thereby leading to slightly higher minimum fuel consumption and nitrogen oxides(NO_(x))emissions.Adding side spark plugs(SSP)based on PPC can result in improved capability of lean limit extension and engine performance than CSP.However,the improvement level is lower than that with triple spark plugs(TSP).As the excess air ratio λ increases,the advantage of PPC and PPC with SSP in improving the combustion phasing compared with CSP gradually weakens.Correspondingly,the increasing tendency of their ignition delay and combustion duration is more obvious.The added SSP based on PPC can effectively shorten the ignition delay of leaner mixture,but the combustion duration can be only slightly improved.As a result,under extremely lean condition,the advantage of PPC and PPC with SSP in terms of combustion characteristics over CSP becomes much smaller.In contrast,the TSP ignition can achieve much shorter ignition delay and combustion duration simultaneously under this condition.Due to the highest available dilution level,the TSP ignition achieves the lowest raw NO_(x)emissions.Moreover,it can also reduce the raw carbon monoxide(CO)and hydrocarbons(HC)emissions compared to CSP due to a more thorough combustion of the end gas mixture.Based on the excellent performance of TSP,the highest engine brake thermal efficiency(BTE)was further explored.The results show that with normal RON 92 fuel,the engine finally achieved 43.69% and 45.02% BTE under stochiometric mode with exhaust gas recirculation(EGR)and lean-burn mode respectively.When using RON 100 fuel,the highest BTE was further increased to 45.63%under lean-burn mode.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
基金the financial support provided by Chongqing Technical Innovation and Application Development Project(cstc2020jscx-dxwtBX0024)China Internal Combustion Engine Society Youth Talent Promotion Program。
文摘In this study,a triple spark ignition scheme was first designed on a three-cylinder 1.5-L dedicated hybrid engine(DHE).On this basis,the effect of different ignition modes on engine combustion and emission characteristics was studied,especially under high dilution condition.The results tested at 2000 r/min and 0.8 MPa BMEP(brake mean effective pressure)show that with highly increased in-cylinder flow intensity,using only passive prechamber(PPC)has a lower lean limit than that with single central spark plug(CSP),thereby leading to slightly higher minimum fuel consumption and nitrogen oxides(NO_(x))emissions.Adding side spark plugs(SSP)based on PPC can result in improved capability of lean limit extension and engine performance than CSP.However,the improvement level is lower than that with triple spark plugs(TSP).As the excess air ratio λ increases,the advantage of PPC and PPC with SSP in improving the combustion phasing compared with CSP gradually weakens.Correspondingly,the increasing tendency of their ignition delay and combustion duration is more obvious.The added SSP based on PPC can effectively shorten the ignition delay of leaner mixture,but the combustion duration can be only slightly improved.As a result,under extremely lean condition,the advantage of PPC and PPC with SSP in terms of combustion characteristics over CSP becomes much smaller.In contrast,the TSP ignition can achieve much shorter ignition delay and combustion duration simultaneously under this condition.Due to the highest available dilution level,the TSP ignition achieves the lowest raw NO_(x)emissions.Moreover,it can also reduce the raw carbon monoxide(CO)and hydrocarbons(HC)emissions compared to CSP due to a more thorough combustion of the end gas mixture.Based on the excellent performance of TSP,the highest engine brake thermal efficiency(BTE)was further explored.The results show that with normal RON 92 fuel,the engine finally achieved 43.69% and 45.02% BTE under stochiometric mode with exhaust gas recirculation(EGR)and lean-burn mode respectively.When using RON 100 fuel,the highest BTE was further increased to 45.63%under lean-burn mode.
