The simulation tests of plume diffusion have been carried out in an open water channel,in which a Laser Doppler Velocitymeter,optical concentration measurement and flow visualization technology have been used.Through ...The simulation tests of plume diffusion have been carried out in an open water channel,in which a Laser Doppler Velocitymeter,optical concentration measurement and flow visualization technology have been used.Through experiments and theoretical analyses,the effects of environmental wind field,surface roughness and discharge condition of elevated source on plume diffusion have been investigated.The plume dif- fusion mechanism has been elucidated reasonably,based on the turbulent coherent structure theory.展开更多
A remote plasma,also referred to as a plasma plume(diffuse or filamentary),is normally formed downstream of an atmospheric pressure plasma jet.In this study,a diffuse plume is formed by increasing the bias voltage(U_(...A remote plasma,also referred to as a plasma plume(diffuse or filamentary),is normally formed downstream of an atmospheric pressure plasma jet.In this study,a diffuse plume is formed by increasing the bias voltage(U_(b))applied to the downstream electrode of an argon plasma jet excited by a negatively pulsed voltage.The results indicate that the plume is filamentary when U_(b)is low,which transits to the diffuse plume with increasing U_(b).The discharge initiated at the rising edge of the pulsed voltage is attributed to the diffuse plume,while that at the falling edge contributes to the filament in the plume.For the diffuse plume,the discharge intensity decreases with the increasing oxygen content(C_o).Fast photography reveals that the diffuse plume results from a negative streamer,which has a dark region near the nozzle with C_o=0%.However,the dark region is absent with C_o=0.5%.From the optical emission spectrum,the electron density,electron excitation temperature,gas temperature,and oxygen atom concentration are investigated.展开更多
In this paper the meteorological background for the formation of plume from the forest fire in Northeast China on 7—8 May 1987 is stated.The long-range instantaneous diffusion parameters are calculated by using the s...In this paper the meteorological background for the formation of plume from the forest fire in Northeast China on 7—8 May 1987 is stated.The long-range instantaneous diffusion parameters are calculated by using the satellite photograph of the plumes with visible length ranging from 100 to over 500 kin.The results of cal- culation show that the relations between instantaneous diffusion parameter and travel time(up to 60000 sec.) obey the law of linear or 3/2 power.In addition,heat release from the fire on May 7—8 estimated by puff rising formula can meet,in respect to the order of magnitude,the value gained on the field survey.展开更多
文摘The simulation tests of plume diffusion have been carried out in an open water channel,in which a Laser Doppler Velocitymeter,optical concentration measurement and flow visualization technology have been used.Through experiments and theoretical analyses,the effects of environmental wind field,surface roughness and discharge condition of elevated source on plume diffusion have been investigated.The plume dif- fusion mechanism has been elucidated reasonably,based on the turbulent coherent structure theory.
基金supported by National Natural Science Foundation of China(Nos.12375250,11875121,51977057 and 11805013)the Natural Science Foundation of Hebei Province(Nos.A2020201025 and A2022201036)+3 种基金Hebei Province Optoelectronic Information Materials Laboratory Performance Subsidy Fund Project(No.22567634H)Funds for Distinguished Young Scientists of Hebei Province(No.A2012201045)the Natural Science Interdisciplinary Research Program of Hebei University(Nos.DXK201908 and DXK202011)the Post-graduate’s Innovation Fund Project of Hebei University(No.HBU2022bs004)。
文摘A remote plasma,also referred to as a plasma plume(diffuse or filamentary),is normally formed downstream of an atmospheric pressure plasma jet.In this study,a diffuse plume is formed by increasing the bias voltage(U_(b))applied to the downstream electrode of an argon plasma jet excited by a negatively pulsed voltage.The results indicate that the plume is filamentary when U_(b)is low,which transits to the diffuse plume with increasing U_(b).The discharge initiated at the rising edge of the pulsed voltage is attributed to the diffuse plume,while that at the falling edge contributes to the filament in the plume.For the diffuse plume,the discharge intensity decreases with the increasing oxygen content(C_o).Fast photography reveals that the diffuse plume results from a negative streamer,which has a dark region near the nozzle with C_o=0%.However,the dark region is absent with C_o=0.5%.From the optical emission spectrum,the electron density,electron excitation temperature,gas temperature,and oxygen atom concentration are investigated.
文摘In this paper the meteorological background for the formation of plume from the forest fire in Northeast China on 7—8 May 1987 is stated.The long-range instantaneous diffusion parameters are calculated by using the satellite photograph of the plumes with visible length ranging from 100 to over 500 kin.The results of cal- culation show that the relations between instantaneous diffusion parameter and travel time(up to 60000 sec.) obey the law of linear or 3/2 power.In addition,heat release from the fire on May 7—8 estimated by puff rising formula can meet,in respect to the order of magnitude,the value gained on the field survey.
