Relight of jet engines at high altitude is difficult due to the relatively low pressure and temperature of inlet air.The penetration of initial flame kernel affects the ignition probability in the turbine engine combu...Relight of jet engines at high altitude is difficult due to the relatively low pressure and temperature of inlet air.The penetration of initial flame kernel affects the ignition probability in the turbine engine combustor greatly.In order to achieve successful ignition at high altitude,a deeper penetration of initial flame kernel should be generated.In this study,a Gliding Arc Plasma Jet Igniter(GAPJI)is designed to induce initial flame kernel with deeper penetration to achieve successful ignition at high altitude.The ignition performance of the GAPJI was demonstrated in a model combustor.It was found that GAPJI can generate plasma with deeper penetration up to 30.5 mm than spark igniter with 22.1 mm.The discharge power of GAPJI was positively correlated with flow rate of the carrier gas,approaching 200 W in average.Ignition experiments show that GAPJI has the advantage of extending the lean ignition limit.With GAPJI,the lean ignition limit of the combustor is 0.02 at 0 km,which is 55.6%less than that with spark igniter(0.045).The evolution of flame morphology was observed to explore the development of the flame kernel.It is shown that the advantage of a high penetration and continuous releasing energy can accelerate the ignition process and enhance combustion.展开更多
The extensional deformation of arc lithosphere is a critical stage in the evolution of subduction systems.Although the tectonic dynamics of well-developed back-arc regions have been widely studied,our understanding of...The extensional deformation of arc lithosphere is a critical stage in the evolution of subduction systems.Although the tectonic dynamics of well-developed back-arc regions have been widely studied,our understanding of nascent arc rifts is still limited.The Southwest Mariana Rift(SWMR),located near the southern Mariana Trench,is currently in its initial rifting stage and serves as an ideal region for studying the evolution of nascent arc rifts.Local ocean bottom seismometer experiments have delineated short-term seismic activities of small earthquakes in the SWMR.However,moderate-sized earthquakes,which reflect long-term predominant rupture behaviors of the rifting faults,are poorly documented.Teleseismic waveforms are the primary data source for studying these moderate-sized earthquakes in the SWMR.Due to the effects of complex 3-D Earth's structures,significant errors can occur in teleseismic source parameter estimation.In this study,we use a novel method to compute 3-D teleseismic Green's functions.By leveraging the sensitivity of teleseismic P coda waveforms to source-side 3-D structural complexities,we effectively improve the accuracy of source location for moderate-sized earthquakes in the SWMR.Centroid depths indicate brittle middle to lower crust,suggesting that the rift crust may be undergoing active initial rifting from shallow to deep.Horizontal locations exhibit cluster distribution characteristics,indicating significant spatial heterogeneities in extensional deformation.Both the middle part and the two tips of the rift show seismicity of moderate-sized earthquakes.Generally,there is no clear evidence of asymmetric extensional deformation.We propose that the rollback of the subducting plate,rather than the collision of the Caroline Plateau,is the main driving force for the opening and evolution of the SWMR.This study provides new evidence for understanding the tectonic evolution of the southwestern Mariana arc.展开更多
基金co-supported by the National Natural Science Foundation of China (Nos. 51807204 and 91941301)the Postdoctoral Research Foundation of China (No. 2019M663719)the National Science and Technology Major Project, China (No. 2017-Ⅲ-0007-0033)
文摘Relight of jet engines at high altitude is difficult due to the relatively low pressure and temperature of inlet air.The penetration of initial flame kernel affects the ignition probability in the turbine engine combustor greatly.In order to achieve successful ignition at high altitude,a deeper penetration of initial flame kernel should be generated.In this study,a Gliding Arc Plasma Jet Igniter(GAPJI)is designed to induce initial flame kernel with deeper penetration to achieve successful ignition at high altitude.The ignition performance of the GAPJI was demonstrated in a model combustor.It was found that GAPJI can generate plasma with deeper penetration up to 30.5 mm than spark igniter with 22.1 mm.The discharge power of GAPJI was positively correlated with flow rate of the carrier gas,approaching 200 W in average.Ignition experiments show that GAPJI has the advantage of extending the lean ignition limit.With GAPJI,the lean ignition limit of the combustor is 0.02 at 0 km,which is 55.6%less than that with spark igniter(0.045).The evolution of flame morphology was observed to explore the development of the flame kernel.It is shown that the advantage of a high penetration and continuous releasing energy can accelerate the ignition process and enhance combustion.
基金supported by the National Natural Science Foundation of China(Grant No.42030311)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515020023)。
文摘The extensional deformation of arc lithosphere is a critical stage in the evolution of subduction systems.Although the tectonic dynamics of well-developed back-arc regions have been widely studied,our understanding of nascent arc rifts is still limited.The Southwest Mariana Rift(SWMR),located near the southern Mariana Trench,is currently in its initial rifting stage and serves as an ideal region for studying the evolution of nascent arc rifts.Local ocean bottom seismometer experiments have delineated short-term seismic activities of small earthquakes in the SWMR.However,moderate-sized earthquakes,which reflect long-term predominant rupture behaviors of the rifting faults,are poorly documented.Teleseismic waveforms are the primary data source for studying these moderate-sized earthquakes in the SWMR.Due to the effects of complex 3-D Earth's structures,significant errors can occur in teleseismic source parameter estimation.In this study,we use a novel method to compute 3-D teleseismic Green's functions.By leveraging the sensitivity of teleseismic P coda waveforms to source-side 3-D structural complexities,we effectively improve the accuracy of source location for moderate-sized earthquakes in the SWMR.Centroid depths indicate brittle middle to lower crust,suggesting that the rift crust may be undergoing active initial rifting from shallow to deep.Horizontal locations exhibit cluster distribution characteristics,indicating significant spatial heterogeneities in extensional deformation.Both the middle part and the two tips of the rift show seismicity of moderate-sized earthquakes.Generally,there is no clear evidence of asymmetric extensional deformation.We propose that the rollback of the subducting plate,rather than the collision of the Caroline Plateau,is the main driving force for the opening and evolution of the SWMR.This study provides new evidence for understanding the tectonic evolution of the southwestern Mariana arc.
