Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-...Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow.展开更多
Underwater pulsed discharge is widely applied in medicine, machining, and material modification.The induced cavitation bubble and subsequent cavitation collapse are considered the major motivations behind these applic...Underwater pulsed discharge is widely applied in medicine, machining, and material modification.The induced cavitation bubble and subsequent cavitation collapse are considered the major motivations behind these applications. This paper presents an underwater pulsed discharge system.The experimental setup is established to induce and investigate the cavitation bubble assisted with a high-speed camera. Three aspects, including the characteristic of the discharge with different applied voltages and conductivities, the evolution of the cavitation bubble profile, and the energy efficiency of cavitation bubble inducing, are investigated, respectively. Especially, the mechanism of pre-discharge time delay in the low field intensity case is explained using the Joule heat effect.The results show the validity of the underwater pulsed discharger and experimental setup. The present underwater pulsed discharger is proved to be a simple, portable, and easy-to-implement device for the investigation of cavitation bubble dynamics.展开更多
In this study,plasma shot(PS)treatment was applied to high-speed steel(HSS)surfaces using a titanium carbide electrode to confirm the effect of discharge current(Ip)on the formation of a single dimple and analyze a mo...In this study,plasma shot(PS)treatment was applied to high-speed steel(HSS)surfaces using a titanium carbide electrode to confirm the effect of discharge current(Ip)on the formation of a single dimple and analyze a modified layer.The roughness of modified surfaces increased when Ip increased,and energy-dispersive X-ray spectrometry showed an increase in titanium atom density whenIp and electrode consumption volume(Ve)increased.A friction test confirmed that the modified surface's friction was reduced by discharge dimples under low-load conditions.Vickers hardness test confirmed that the hardness of the modified surface was-300-600 HV higher than that of an untreated HSS surface.Moreover,it increased with an increase inIp.However,application of PS treatment to the edge of surfaces on the workpiece caused shape deterioration.The deterioration size of the edge of the modified layer increased when Ip increased.To solve this issue,we propose a novel method named position-adjusted PS(PA-PS)treatment.PA-PS treatment is used to adjust the end of the electrode in the order of tens of micrometers from the edge of the workpiece to avoid the deterioration of the edge form.Under Ip=21 A,PA-PS formed a modified layer without deteriorating the edge shape of the workpiece,thus confirming the PS characteristics applied to HSS surfaces.Moreover,PA-PS treatment solved the shape deterioration of the edge on modified surfaces via PS treatment.展开更多
文摘Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow.
基金supported by National Natural Science Foundation of China (Grant Nos. 11874140, 11574072)National Key Research and Development Program of China (Grant No. 2016YFC0401600)+2 种基金Primary Research and Development Plan of Jiangsu Province, China (Grant No. BE2016056)Fundamental Research Funds for the Central Universities (Grant No. 2017B17814)Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No. KYCX18_0552)
文摘Underwater pulsed discharge is widely applied in medicine, machining, and material modification.The induced cavitation bubble and subsequent cavitation collapse are considered the major motivations behind these applications. This paper presents an underwater pulsed discharge system.The experimental setup is established to induce and investigate the cavitation bubble assisted with a high-speed camera. Three aspects, including the characteristic of the discharge with different applied voltages and conductivities, the evolution of the cavitation bubble profile, and the energy efficiency of cavitation bubble inducing, are investigated, respectively. Especially, the mechanism of pre-discharge time delay in the low field intensity case is explained using the Joule heat effect.The results show the validity of the underwater pulsed discharger and experimental setup. The present underwater pulsed discharger is proved to be a simple, portable, and easy-to-implement device for the investigation of cavitation bubble dynamics.
文摘In this study,plasma shot(PS)treatment was applied to high-speed steel(HSS)surfaces using a titanium carbide electrode to confirm the effect of discharge current(Ip)on the formation of a single dimple and analyze a modified layer.The roughness of modified surfaces increased when Ip increased,and energy-dispersive X-ray spectrometry showed an increase in titanium atom density whenIp and electrode consumption volume(Ve)increased.A friction test confirmed that the modified surface's friction was reduced by discharge dimples under low-load conditions.Vickers hardness test confirmed that the hardness of the modified surface was-300-600 HV higher than that of an untreated HSS surface.Moreover,it increased with an increase inIp.However,application of PS treatment to the edge of surfaces on the workpiece caused shape deterioration.The deterioration size of the edge of the modified layer increased when Ip increased.To solve this issue,we propose a novel method named position-adjusted PS(PA-PS)treatment.PA-PS treatment is used to adjust the end of the electrode in the order of tens of micrometers from the edge of the workpiece to avoid the deterioration of the edge form.Under Ip=21 A,PA-PS formed a modified layer without deteriorating the edge shape of the workpiece,thus confirming the PS characteristics applied to HSS surfaces.Moreover,PA-PS treatment solved the shape deterioration of the edge on modified surfaces via PS treatment.
