Mutual effects between a gliding arc(GA)discharge at atmospheric pressure and a premixed CH_(4)/air flame were experimentally investigated.Effects of the flame on the GA were studied using simultaneous measurements of...Mutual effects between a gliding arc(GA)discharge at atmospheric pressure and a premixed CH_(4)/air flame were experimentally investigated.Effects of the flame on the GA were studied using simultaneous measurements of the current,the voltage,and the instantaneous images of the plasma columns.The GA in the flame has a thicker and more diffusive plasma column,and it is more frequently ignited at a smaller breakdown voltage than that in the air.The GA extension velocity and the gliding velocity in the flame are larger than those in the air.The electrode voltage drop of the GA discharge in the flame is about 160 V,whereas that in the air is about 220 V.Compared with the GA in the air,the different features of the GA in the flame can be explained by high-temperature,weakly ionized,and species-abundant environment that are generated by the premixed CH_(4)/air flame.Effects of the gliding arc discharge on the premixed flames were demonstrated using planar laser-induced fluorescence of hydroxyl radicals(OH)and formaldehyde(CH_(2)O).OH and CH_(2)O can be formed in the CH_(4)/air mixture in the presence of the GA due to kinetic effects,and the increase of OH and CH_(2)O shows the great potential of the GA for combustion enhancement.展开更多
The combustion chamber is the core component of an aero-engine, and affects its reliability and security operation, even the performance of the aircraft. In this work, a Plasma-Assisted Combustion(PAC) test platform w...The combustion chamber is the core component of an aero-engine, and affects its reliability and security operation, even the performance of the aircraft. In this work, a Plasma-Assisted Combustion(PAC) test platform was developed to validate the feasibility of using PAC actuators to enhance annular combustor performance. Two plans of PAC(rotating gliding arc discharge plasma) were designed, Assisted Combustion from Primary Holes(ACPH) and Assisted Combustion from Dilution Holes(ACDH). Comparative experiments and analysis between conventional combustion and PAC were conducted to study the effects of ACPH and ACDH on the performances including average outlet temperature, combustion efficiency, pattern factor under four different excessive air coefficients(0.8, 1, 2, and 4), and lean blowout performance at different inlet airflow velocities. Experimental results show that the combustion efficiency is improved after PAC compared with that in normal conditions, and the combustion efficiency of ACPH increases2.45%, 1.49%, 1.04%, and 0.47%, while it increases 2.75%, 1.67%, 1.36%, and 0.36% under ACDH conditions. The uniformity of the outlet temperature field and the lean blowout performance are improved after PAC. Especially for ACPH, the widening of the lean blowout limit is8.3%, 12.4%, 12.8%, and 25% respectively when the inlet velocity ranges from 60 m/s to120 m/s. These results offer new perspectives for using PAC devices to enhance aero-engine combustors' performances.展开更多
将滑动弧等离子体运用在Ma=2.92的乙烯燃料超声速燃烧室中,运用40 k Hz CH*自发辐射,电流电压探针和压力传感器进行诊断。针对不同当量比研究了滑动弧等离子体对超声速火焰的燃烧增强效果,并观测到滑动弧等离子体的稳焰现象。结果表明,...将滑动弧等离子体运用在Ma=2.92的乙烯燃料超声速燃烧室中,运用40 k Hz CH*自发辐射,电流电压探针和压力传感器进行诊断。针对不同当量比研究了滑动弧等离子体对超声速火焰的燃烧增强效果,并观测到滑动弧等离子体的稳焰现象。结果表明,超声速燃烧中滑动弧等离子体有助燃作用,在当量比为0.12和0.16时助燃效果更明显,而对于贫燃工况助燃效果不明显。在全局当量比为0.16时,施加滑动弧等离子体后壁面压力平均提升12%,时均火焰面积提升27%。原因是等离子体和凹腔结合作用,强化了凹腔给主流火焰提供热量和自由基的作用。同时,再点火生成的初始火核能够传播至凹腔驻留区,在燃烧不稳定工况下有助于超声速火焰的稳定。展开更多
基金financially supported by National Natural Science Foundation of China(Nos.12172379,12322211,and 11925207)。
文摘Mutual effects between a gliding arc(GA)discharge at atmospheric pressure and a premixed CH_(4)/air flame were experimentally investigated.Effects of the flame on the GA were studied using simultaneous measurements of the current,the voltage,and the instantaneous images of the plasma columns.The GA in the flame has a thicker and more diffusive plasma column,and it is more frequently ignited at a smaller breakdown voltage than that in the air.The GA extension velocity and the gliding velocity in the flame are larger than those in the air.The electrode voltage drop of the GA discharge in the flame is about 160 V,whereas that in the air is about 220 V.Compared with the GA in the air,the different features of the GA in the flame can be explained by high-temperature,weakly ionized,and species-abundant environment that are generated by the premixed CH_(4)/air flame.Effects of the gliding arc discharge on the premixed flames were demonstrated using planar laser-induced fluorescence of hydroxyl radicals(OH)and formaldehyde(CH_(2)O).OH and CH_(2)O can be formed in the CH_(4)/air mixture in the presence of the GA due to kinetic effects,and the increase of OH and CH_(2)O shows the great potential of the GA for combustion enhancement.
基金supported by the National Natural Science Foundation of China (No. 51436008)
文摘The combustion chamber is the core component of an aero-engine, and affects its reliability and security operation, even the performance of the aircraft. In this work, a Plasma-Assisted Combustion(PAC) test platform was developed to validate the feasibility of using PAC actuators to enhance annular combustor performance. Two plans of PAC(rotating gliding arc discharge plasma) were designed, Assisted Combustion from Primary Holes(ACPH) and Assisted Combustion from Dilution Holes(ACDH). Comparative experiments and analysis between conventional combustion and PAC were conducted to study the effects of ACPH and ACDH on the performances including average outlet temperature, combustion efficiency, pattern factor under four different excessive air coefficients(0.8, 1, 2, and 4), and lean blowout performance at different inlet airflow velocities. Experimental results show that the combustion efficiency is improved after PAC compared with that in normal conditions, and the combustion efficiency of ACPH increases2.45%, 1.49%, 1.04%, and 0.47%, while it increases 2.75%, 1.67%, 1.36%, and 0.36% under ACDH conditions. The uniformity of the outlet temperature field and the lean blowout performance are improved after PAC. Especially for ACPH, the widening of the lean blowout limit is8.3%, 12.4%, 12.8%, and 25% respectively when the inlet velocity ranges from 60 m/s to120 m/s. These results offer new perspectives for using PAC devices to enhance aero-engine combustors' performances.
文摘将滑动弧等离子体运用在Ma=2.92的乙烯燃料超声速燃烧室中,运用40 k Hz CH*自发辐射,电流电压探针和压力传感器进行诊断。针对不同当量比研究了滑动弧等离子体对超声速火焰的燃烧增强效果,并观测到滑动弧等离子体的稳焰现象。结果表明,超声速燃烧中滑动弧等离子体有助燃作用,在当量比为0.12和0.16时助燃效果更明显,而对于贫燃工况助燃效果不明显。在全局当量比为0.16时,施加滑动弧等离子体后壁面压力平均提升12%,时均火焰面积提升27%。原因是等离子体和凹腔结合作用,强化了凹腔给主流火焰提供热量和自由基的作用。同时,再点火生成的初始火核能够传播至凹腔驻留区,在燃烧不稳定工况下有助于超声速火焰的稳定。
