The primary issue regarding the plasma synthetic jet actuator(PSJA)is its performance attenuation at high frequencies.To solve this issue,a self-supplementing,dual-cavity,plasma synthetic jet actuator(SD-PSJA)is desig...The primary issue regarding the plasma synthetic jet actuator(PSJA)is its performance attenuation at high frequencies.To solve this issue,a self-supplementing,dual-cavity,plasma synthetic jet actuator(SD-PSJA)is designed,and the static properties of the SD-PSJA are investigated through experiments and numerical simulations.The pressure measurement shows that the SD-PSJA has two saturation frequencies(1200 Hz and 2100 Hz),and the experimental results show that both the saturation frequencies decrease as the volume of the bottom cavity of the SD-PSJA increases.As the size of the supplement hole increases,the first saturation frequency increases continuously,while the second saturation frequency shows a trend of first decreasing and then increasing.Numerical simulations show that the working process of the SD-PSJA is similar to that of the PSJA,but the volume of the cavity in the SD-PSJA is smaller than that of the PSJA;the SD-PSJA can supplement air to the top cavity through two holes,thus reducing the refresh time and effectively improving the jet intensity of the actuator at high frequencies.展开更多
An array of 30 plasma synthetic jet actuators(PSJAs)is deployed using a modified multichannel discharge circuit to suppress the flow separation over a straight-wing model.The lift and drag of the wing model are measur...An array of 30 plasma synthetic jet actuators(PSJAs)is deployed using a modified multichannel discharge circuit to suppress the flow separation over a straight-wing model.The lift and drag of the wing model are measured by a force balance,and the velocity fields over the suction surface are captured by a particle imaging velocimetry system.Results show that the flow separation of the straight wing originates from the middle of the model and expands towards the wingtips as the angle of attack increases.The flow separation can be suppressed effectively by the PSJAs array.The best flow control effect is achieved at a dimensionless discharge frequency of F^+=1,with the peak lift coefficient increased by 10.5%and the stall angle postponed by 2°.To further optimize the power consumption of the PSJAs,the influence of the density of PSJAs on the flow control effect is investigated.A threshold of the density exits(with the spanwise spacing of PSJAs being 0.2 times of the chord length in the current research),below which the flow control effect starts to deteriorate remarkably.In addition,for comparison purposes,a dielectric barrier discharge(DBD)plasma actuator is installed at the same location of the PSJAs.At the same power consumption,4.9%increase of the peak lift coefficient is achieved by DBD,while that achieved by PSJAs reaches 5.6%.展开更多
The effect of nanosecond pulsed dielectric barrier discharge(NS-DBD) plasma flow separation control is closely related to the actuation frequency,because it involves the interaction between plasma-induced vortexes and...The effect of nanosecond pulsed dielectric barrier discharge(NS-DBD) plasma flow separation control is closely related to the actuation frequency,because it involves the interaction between plasma-induced vortexes and separated flow.In order to study the mechanism of NS-DBD plasma flow separation control over a swept wing,especially the influence of the actuation frequency,at first,experimental studies of the actuation frequencies at 100 Hz are conducted to validate the numerical simulation method.Then,numerical studies of different actuation frequencies which are 50 Hz,100 Hz,160 Hz,200 Hz,500 Hz,and 1000 Hz,respectively are conducted.The interaction between the plasma-induced vortexes and the separated flow is analyzed.Results show that there is a range of the actuation frequency which includes the frequency(160 Hz) calculated by the average aerodynamic chord length to make the control effect good,but when the actuation frequencies are too low(50 Hz) or too high(1000 Hz),the control effect will get worse.The former is because plasmainduced vortexes disappear in a period within an actuation cycle;the latter is because plasma-induced vortexes cannot develop completely,resulting in a weak vortex intensity.展开更多
Tri-electrode sliding discharge(TED)plasma actuators are formed by adding a direct current(DC)exposed electrode to conventional dielectric barrier discharge(DBD)plasma actuators.There are three TED modes depending on ...Tri-electrode sliding discharge(TED)plasma actuators are formed by adding a direct current(DC)exposed electrode to conventional dielectric barrier discharge(DBD)plasma actuators.There are three TED modes depending on the polarity and amplitude of the DC supply:DBD discharge,extended discharge and sliding discharge.This paper evaluates the electrical,aerodynamic and mechanical characteristics of a TED plasma actuator based on energy analysis,particle image velocimetry experiments and calculations using the Navier-Stokes equation.The flow control performances of different discharge modes are quantitatively analyzed based on characteristic parameters.The results show that flow control performance in both extended discharge and sliding discharge is more significant than that of DBD,mainly because of the significantly higher(up to 141%)body force of TED compared with DBD.However,conductivity loss is the primary power loss caused by the DC polarity for TED discharge.Therefore,power consumption can be reduced by optimizing the dielectric material and thickness,thus improving the flow control performance of plasma actuators.展开更多
Plasma flow control technology has broad prospects for application.Compared with conventional dielectric barrier discharge plasma actuators(DBD-PA),the sliding discharge plasma actuator(SD-PA)has the advantages of a l...Plasma flow control technology has broad prospects for application.Compared with conventional dielectric barrier discharge plasma actuators(DBD-PA),the sliding discharge plasma actuator(SD-PA)has the advantages of a large discharge area and a deflectable induced jet.To achieve the basic performance requirements of light weight,low cost,and high reliability required for UAV(Unmanned Aerial Vehicle)plasma flight experiments,this work designed a microsecond pulse plasma supply that can be used for sliding discharge plasma actuators.In this study,the topology of the primary circuit of the microsecond pulse supply is determined,the waveform of the output terminal of the microsecond pulse plasma supply is detected using the Simulink simulation platform,and the design of the actuation voltage,the pulse frequency modulation function and the construction of the hardware circuit are achieved.Using electrical diagnosis and flow field analysis,the actuation characteristics and flow characteristics of sliding discharge plasma under microsecond pulse actuation are studied,the optimal electrical actuation parameters and flow field characteristics are described.展开更多
Developing all-solid-state polymer electrolytes(SPEs) with high electrochemical performances and stability is of great importance for exploiting of high energy density and safe batteries. Herein, ether linkage and imi...Developing all-solid-state polymer electrolytes(SPEs) with high electrochemical performances and stability is of great importance for exploiting of high energy density and safe batteries. Herein, ether linkage and imidazolium ionic liquid(ILs) are incorporated into the multi-armed polymer backbone though the series and parallel way. The parallel polymeric ionic liquid(P-P(PEGMA-IM)) maximizes the synergistic effect of ILs and ether linkage, which endowed the material with low crystallinity and high flame retardancy. The P-P(PEGMA-IM) based P-SPE presents a high ionic conductivity of 0.489 m S/cm at 60°C, an excellent lithium-ion transference number of 0.46 and a wide electrochemical window of 4.87 V.The assembled lithium metal battery using P-SPE can deliver a capacity of 151 m Ah/g at 0.2 C, and the capacity retention ratio reaches 82% with a columbic efficiency beyond 99%. The overpotential of P-SPE based symmetric battery is 0.08 V, and there is no apparent magnifying even after 130 h cycling. This new design provides a new avenue for exploitation of advanced SPEs for the next-generation batteries.展开更多
This work studies the turbulent drag reduction(TDR)effect of a flat plate model using a spanwise slot blowing pulsed plasma actuator(SBP-PA).Wind tunnel experiments are carried out under a Reynolds number of 1.445...This work studies the turbulent drag reduction(TDR)effect of a flat plate model using a spanwise slot blowing pulsed plasma actuator(SBP-PA).Wind tunnel experiments are carried out under a Reynolds number of 1.445×10^(4).Using a hot-wire anemometer and an electrical data acquisition system,the influences of millisecond pulsed plasma actuation with different burst frequencies and duty cycles on the microscale coherent structures near the wall of the turbulent boundary layer(TBL)are studied.The experimental results show that the SBP-PA can effectively reduce the frictional drag of the TBL.When the duty cycle exceeds 30%,the TDR rate is greater than 11%,and the optimal drag reduction rate of 13.69%is obtained at a duty cycle of 50%.Furthermore,optimizing the electrical parameters reveals that increasing the burst frequency significantly reduces the velocity distribution in the logarithmic region of the TBL.When the normalized burst frequency reaches f+=2πf_(p)d/U_(∞)=7.196,the optimal TDR effectiveness is 16.97%,indicating a resonance phenomenon between the pulsed plasma actuation and the microscale coherent structures near the wall.Therefore,reasonably selecting the electrical parameters of the plasma actuator is expected to significantly improve the TDR effect.展开更多
Dielectric Barrier Discharge(DBD)based turbulent drag reduction methods are used to reduce the total drag on a NACA 0012 airfoil at low angels of attack.The interaction of DBD with turbulent boundary layer was investi...Dielectric Barrier Discharge(DBD)based turbulent drag reduction methods are used to reduce the total drag on a NACA 0012 airfoil at low angels of attack.The interaction of DBD with turbulent boundary layer was investigated,based on which the drag reduction experiments were conducted.The results show that unidirectional steady discharge is more effective than oscillating discharge in terms of drag reduction,while steady impinging discharge fails to finish the mission(i.e.drag increase).In the best scenario,a maximum relative drag reduction as high as 64%is achieved at the freestream velocity of 5 m/s,and a drag reduction of 13.7%keeps existing at the freestream velocity of 20 m/s.For unidirectional discharge,the jet velocity ratio and the dimensionless actuator spacing are the two key parameters affecting the effectiveness.The drag reduction magnitude varies inversely with the dimensionless spacing,and a threshold value of the dimensionless actuator spac-ing of 540(approximately five times of the low-speed streak spacing)exists,above which the drag increases.When the jet velocity ratio smaller than 0.05,marginal drag variation is observed.In con-trast,when the jet velocity ratio larger than 0.05,the experimental data bifurcates,one into the drag increase zone and the other into the drag reduction zone,depending on the value of dimensionless actuator spacing.In both zones,the drag variation magnitude increases with the jet velocity ratio.The total drag reduction can be divided into the reduction in pressure drag and turbulent friction drag,as well as the increase in friction drag brought by transition promotion.The reduction in tur-bulent friction drag plays an important role in the total drag reduction.展开更多
Holding a promise of achieving high power and energy densities,Li-ion hybrid electrochemical capacitors present a crucial future direction for energy storage devices.However,technical challenges remain to appropriatel...Holding a promise of achieving high power and energy densities,Li-ion hybrid electrochemical capacitors present a crucial future direction for energy storage devices.However,technical challenges remain to appropriately couple both high-power capacitor-type and high-energy battery-type electrode materials within a same device.In addition,the current electrode materials in the device are usually prepared separately,which leads to lengthy preparation,time-consuming and high-cost.In this work,we report a simple method to prepare porous carbon materials(PC) with and without MnO nanoparticle cores,which function as very unique anode/cathode pairs for very high-performance Li ion hybrid supercapacitor.Taking the respective merits of high Li storage capacity from the MnO@C anode and high-rate performance from the PC cathode,the resulted device exhibits a remarkable energy density of 89 Wh·kg^(-1)(at 48 W·kg^(-1)) and can reach a battery-inaccessible power density of 18 kW·kg^(-1)(at 45Wh·kg^(-1)).展开更多
基金National Natural Science Foundation of China(No.61971345)the Foundation for Key Laboratories of National Defense Science and Technology of China(No.614220120030810).
文摘The primary issue regarding the plasma synthetic jet actuator(PSJA)is its performance attenuation at high frequencies.To solve this issue,a self-supplementing,dual-cavity,plasma synthetic jet actuator(SD-PSJA)is designed,and the static properties of the SD-PSJA are investigated through experiments and numerical simulations.The pressure measurement shows that the SD-PSJA has two saturation frequencies(1200 Hz and 2100 Hz),and the experimental results show that both the saturation frequencies decrease as the volume of the bottom cavity of the SD-PSJA increases.As the size of the supplement hole increases,the first saturation frequency increases continuously,while the second saturation frequency shows a trend of first decreasing and then increasing.Numerical simulations show that the working process of the SD-PSJA is similar to that of the PSJA,but the volume of the cavity in the SD-PSJA is smaller than that of the PSJA;the SD-PSJA can supplement air to the top cavity through two holes,thus reducing the refresh time and effectively improving the jet intensity of the actuator at high frequencies.
基金National Natural Science Foundation of China(Nos.12002384 and 11802341)the National Key Laboratory Foundation of China(No.614220210200112)the Academician Workstation Foundation of the Green Aerotechnics Research Institute of Chongqing Jiaotong University(No.GATRI2020C06003)。
文摘An array of 30 plasma synthetic jet actuators(PSJAs)is deployed using a modified multichannel discharge circuit to suppress the flow separation over a straight-wing model.The lift and drag of the wing model are measured by a force balance,and the velocity fields over the suction surface are captured by a particle imaging velocimetry system.Results show that the flow separation of the straight wing originates from the middle of the model and expands towards the wingtips as the angle of attack increases.The flow separation can be suppressed effectively by the PSJAs array.The best flow control effect is achieved at a dimensionless discharge frequency of F^+=1,with the peak lift coefficient increased by 10.5%and the stall angle postponed by 2°.To further optimize the power consumption of the PSJAs,the influence of the density of PSJAs on the flow control effect is investigated.A threshold of the density exits(with the spanwise spacing of PSJAs being 0.2 times of the chord length in the current research),below which the flow control effect starts to deteriorate remarkably.In addition,for comparison purposes,a dielectric barrier discharge(DBD)plasma actuator is installed at the same location of the PSJAs.At the same power consumption,4.9%increase of the peak lift coefficient is achieved by DBD,while that achieved by PSJAs reaches 5.6%.
基金National Science and Technology Major Project (No.J2019-Ⅱ-0014-0035)Academician Workstation Foundation of the Green Aerotechnics Research Institute of Chonging Jiaotong University (No. GATRI2020C06003)。
文摘The effect of nanosecond pulsed dielectric barrier discharge(NS-DBD) plasma flow separation control is closely related to the actuation frequency,because it involves the interaction between plasma-induced vortexes and separated flow.In order to study the mechanism of NS-DBD plasma flow separation control over a swept wing,especially the influence of the actuation frequency,at first,experimental studies of the actuation frequencies at 100 Hz are conducted to validate the numerical simulation method.Then,numerical studies of different actuation frequencies which are 50 Hz,100 Hz,160 Hz,200 Hz,500 Hz,and 1000 Hz,respectively are conducted.The interaction between the plasma-induced vortexes and the separated flow is analyzed.Results show that there is a range of the actuation frequency which includes the frequency(160 Hz) calculated by the average aerodynamic chord length to make the control effect good,but when the actuation frequencies are too low(50 Hz) or too high(1000 Hz),the control effect will get worse.The former is because plasmainduced vortexes disappear in a period within an actuation cycle;the latter is because plasma-induced vortexes cannot develop completely,resulting in a weak vortex intensity.
基金the National Natural Science Foundation of China(Grant Nos.12175177 and 61971345)the Foundation for Key Laboratories of National Defense Science and Technology of China(Grant No.614220120030810)。
文摘Tri-electrode sliding discharge(TED)plasma actuators are formed by adding a direct current(DC)exposed electrode to conventional dielectric barrier discharge(DBD)plasma actuators.There are three TED modes depending on the polarity and amplitude of the DC supply:DBD discharge,extended discharge and sliding discharge.This paper evaluates the electrical,aerodynamic and mechanical characteristics of a TED plasma actuator based on energy analysis,particle image velocimetry experiments and calculations using the Navier-Stokes equation.The flow control performances of different discharge modes are quantitatively analyzed based on characteristic parameters.The results show that flow control performance in both extended discharge and sliding discharge is more significant than that of DBD,mainly because of the significantly higher(up to 141%)body force of TED compared with DBD.However,conductivity loss is the primary power loss caused by the DC polarity for TED discharge.Therefore,power consumption can be reduced by optimizing the dielectric material and thickness,thus improving the flow control performance of plasma actuators.
基金supported by National Natural Science Foundation of China(No.61971345)the Foundation for Key Laboratories of National Defense Science and Technology of China(No.614220120030810)Shaanxi Provincial Key R&D Program General Project(No.2021GY-044)。
文摘Plasma flow control technology has broad prospects for application.Compared with conventional dielectric barrier discharge plasma actuators(DBD-PA),the sliding discharge plasma actuator(SD-PA)has the advantages of a large discharge area and a deflectable induced jet.To achieve the basic performance requirements of light weight,low cost,and high reliability required for UAV(Unmanned Aerial Vehicle)plasma flight experiments,this work designed a microsecond pulse plasma supply that can be used for sliding discharge plasma actuators.In this study,the topology of the primary circuit of the microsecond pulse supply is determined,the waveform of the output terminal of the microsecond pulse plasma supply is detected using the Simulink simulation platform,and the design of the actuation voltage,the pulse frequency modulation function and the construction of the hardware circuit are achieved.Using electrical diagnosis and flow field analysis,the actuation characteristics and flow characteristics of sliding discharge plasma under microsecond pulse actuation are studied,the optimal electrical actuation parameters and flow field characteristics are described.
基金National Natural Science Foundation of China (No. 51303083)the Natural Science Foundation of Jiangsu Province (No. BK20191293)the Fundamental Research Funds for the Central Universities (No. 30920021123) for financial support。
文摘Developing all-solid-state polymer electrolytes(SPEs) with high electrochemical performances and stability is of great importance for exploiting of high energy density and safe batteries. Herein, ether linkage and imidazolium ionic liquid(ILs) are incorporated into the multi-armed polymer backbone though the series and parallel way. The parallel polymeric ionic liquid(P-P(PEGMA-IM)) maximizes the synergistic effect of ILs and ether linkage, which endowed the material with low crystallinity and high flame retardancy. The P-P(PEGMA-IM) based P-SPE presents a high ionic conductivity of 0.489 m S/cm at 60°C, an excellent lithium-ion transference number of 0.46 and a wide electrochemical window of 4.87 V.The assembled lithium metal battery using P-SPE can deliver a capacity of 151 m Ah/g at 0.2 C, and the capacity retention ratio reaches 82% with a columbic efficiency beyond 99%. The overpotential of P-SPE based symmetric battery is 0.08 V, and there is no apparent magnifying even after 130 h cycling. This new design provides a new avenue for exploitation of advanced SPEs for the next-generation batteries.
基金supported by National Natural Science Foundation of China(Nos.61971345 and 12175177)the Foundation for Key Laboratories of National Defense Science and Technology of China(No.614220120030810).
文摘This work studies the turbulent drag reduction(TDR)effect of a flat plate model using a spanwise slot blowing pulsed plasma actuator(SBP-PA).Wind tunnel experiments are carried out under a Reynolds number of 1.445×10^(4).Using a hot-wire anemometer and an electrical data acquisition system,the influences of millisecond pulsed plasma actuation with different burst frequencies and duty cycles on the microscale coherent structures near the wall of the turbulent boundary layer(TBL)are studied.The experimental results show that the SBP-PA can effectively reduce the frictional drag of the TBL.When the duty cycle exceeds 30%,the TDR rate is greater than 11%,and the optimal drag reduction rate of 13.69%is obtained at a duty cycle of 50%.Furthermore,optimizing the electrical parameters reveals that increasing the burst frequency significantly reduces the velocity distribution in the logarithmic region of the TBL.When the normalized burst frequency reaches f+=2πf_(p)d/U_(∞)=7.196,the optimal TDR effectiveness is 16.97%,indicating a resonance phenomenon between the pulsed plasma actuation and the microscale coherent structures near the wall.Therefore,reasonably selecting the electrical parameters of the plasma actuator is expected to significantly improve the TDR effect.
基金co-supported by the National Natural Science Foundation of China(Nos.12002384,11802341)the National Key Laboratory Foundation of China(No.614220210200112)+1 种基金the National Science and Technology Major Project,China(No.J2019-II-0014-0035)the Aca-demician Workstation Foundation of the Green Aerotechnics Research Institute of Chongqing Jiaotong University,China(No.GATRI2020C06003).
文摘Dielectric Barrier Discharge(DBD)based turbulent drag reduction methods are used to reduce the total drag on a NACA 0012 airfoil at low angels of attack.The interaction of DBD with turbulent boundary layer was investigated,based on which the drag reduction experiments were conducted.The results show that unidirectional steady discharge is more effective than oscillating discharge in terms of drag reduction,while steady impinging discharge fails to finish the mission(i.e.drag increase).In the best scenario,a maximum relative drag reduction as high as 64%is achieved at the freestream velocity of 5 m/s,and a drag reduction of 13.7%keeps existing at the freestream velocity of 20 m/s.For unidirectional discharge,the jet velocity ratio and the dimensionless actuator spacing are the two key parameters affecting the effectiveness.The drag reduction magnitude varies inversely with the dimensionless spacing,and a threshold value of the dimensionless actuator spac-ing of 540(approximately five times of the low-speed streak spacing)exists,above which the drag increases.When the jet velocity ratio smaller than 0.05,marginal drag variation is observed.In con-trast,when the jet velocity ratio larger than 0.05,the experimental data bifurcates,one into the drag increase zone and the other into the drag reduction zone,depending on the value of dimensionless actuator spacing.In both zones,the drag variation magnitude increases with the jet velocity ratio.The total drag reduction can be divided into the reduction in pressure drag and turbulent friction drag,as well as the increase in friction drag brought by transition promotion.The reduction in tur-bulent friction drag plays an important role in the total drag reduction.
基金financially supported by the National Natural Science Foundation of China (Nos.11632004, 52005151 and U1864208)the Research Program of Local Science and Technology Development under the Guidance of Central (No. 216Z4402G)+6 种基金the National Science and Technology Major Project (No.2017-Ⅶ-0011-0106)the Science and Technology Planning Project of Tianjin (No.20ZYJDJC00030)the Key Program of Research and Development of Hebei Province (No. 202030507040009)the Fund for Innovative Research Groups of Natural Science Foundation of Hebei Province (No.A2020202002)the Key Project of Natural Science Foundation of Tianjin (No. S20ZDF077)support from the Open Project Found of Chongqing Key Laboratory of Green(No.GATRI2021F01005B)support from "Yuanguang" Scholar Program of Hebei University of Technology。
文摘Holding a promise of achieving high power and energy densities,Li-ion hybrid electrochemical capacitors present a crucial future direction for energy storage devices.However,technical challenges remain to appropriately couple both high-power capacitor-type and high-energy battery-type electrode materials within a same device.In addition,the current electrode materials in the device are usually prepared separately,which leads to lengthy preparation,time-consuming and high-cost.In this work,we report a simple method to prepare porous carbon materials(PC) with and without MnO nanoparticle cores,which function as very unique anode/cathode pairs for very high-performance Li ion hybrid supercapacitor.Taking the respective merits of high Li storage capacity from the MnO@C anode and high-rate performance from the PC cathode,the resulted device exhibits a remarkable energy density of 89 Wh·kg^(-1)(at 48 W·kg^(-1)) and can reach a battery-inaccessible power density of 18 kW·kg^(-1)(at 45Wh·kg^(-1)).
