Active flow control based on surface dielectric barrier discharge（SDBD） has become a focus of research in recent years,due to its unique advantages and diverse potential applications.Compared with the conventional S...Active flow control based on surface dielectric barrier discharge（SDBD） has become a focus of research in recent years,due to its unique advantages and diverse potential applications.Compared with the conventional SDBD with straight electrodes,the serrated electrode-based SDBD has a great advantage due to its 3D flow topology.It is believed that the boundary layer separation of moving objects can be controlled more effectively with this new type of SDBD.In SDBD with a serrated electrode,the R（tip sharpness） and N（tip number per unit length） have a great influence on the discharge and induced airflow characteristics.In this paper,a parametric study of the characteristics of SDBD with a serrated electrode has been conducted with different ranges of R and N.Aspects of the power consumption,the steady medium temperature distribution,and the maximum induced airflow velocity have been investigated.The results indicate that there is a critical value of R and N where the maximum power consumption and induced airflow velocity are achieved.The uniformity of the steady temperature distribution of the medium surface is found to be more dependent on N.We found that the accelerating effects of the induced airflow can be evaluated with the Schlieren technique,which agree well with the results from the pitot tube.展开更多
Improving energy efficiency in plasma NO removal is a critical issue.When the surface dielectric barrier discharge(SDBD)device is considered as a combination of multiple plasma actuators,the induced plasma aerodynamic...Improving energy efficiency in plasma NO removal is a critical issue.When the surface dielectric barrier discharge(SDBD)device is considered as a combination of multiple plasma actuators,the induced plasma aerodynamic effect cannot be ignored,which can affect the mass transfer,then affect the chemical reactions.Five SDBD devices with different electrode arrangements are studied for NO conversion.They correspond to different flow patterns.We find that the energy efficiency in an SDBD device with a common structure(Type 1)is 28%lower than that in SDBD devices with a special arrangement(Types 2–5).Two reasons may explain the results.First,fewer active species are produced in Type 1 because the development of discharge is hindered by the mutually exclusive electric field forces caused by the symmetrically distributed charged particles.Second,the plasma wind induced by the plasma actuator can enhance the mass and heat transfer.The mixing of reactants and products is better in Types 2–5 than Type 1 due to higher turbulence kinetic energy.展开更多
The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study t...The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.展开更多
Flow fields induced by a surface dielectric barrier discharge actuator at low pressure of 7 kPa are measured by particle image velocimetry. The distribution of local vortices in the flow field is revealed by the Q cri...Flow fields induced by a surface dielectric barrier discharge actuator at low pressure of 7 kPa are measured by particle image velocimetry. The distribution of local vortices in the flow field is revealed by the Q criterion. The reason for the generation of vortices is analyzed and the influence of pulse frequency and duty cycle on vortices is studied. The results show that the Q criterion can reveal the small-scale vortices, which cannot be indicated by the streamline. The direction transition zone where the induced jet moves from the vertical to the tangential and the shear layer between the jet and stationary air are prone to the generation of strong vortices. The influence of pulse frequency on vortices is not obvious, but the variation of duty cycle can significantly affect the strength and distribution of vortices.展开更多
A surface dielectric barrier discharge (SDBD) can discharge at atmospheric pressure and produce a large area of low-temperature plasma.An SDBD plasma reactor based on the double spiral structure is introduced in this ...A surface dielectric barrier discharge (SDBD) can discharge at atmospheric pressure and produce a large area of low-temperature plasma.An SDBD plasma reactor based on the double spiral structure is introduced in this paper.To study the discharge mechanism of SDBD,an equivalent circuit model was proposed based on the analysis of the micro-discharge process of SDBD.Matlab/Simulink is used to simulate and compare the voltage-current waves,Lissajous and discharge power with the experimental results.The consistency of the results verifies the validity of the SDBD equivalent circuit model.Maxwell software based on the finite elements method is used to analyze the electrostatic field distribution of the device,which can better explain the relationship between the discharge image and the electrostatic field distribution.The combination of equivalent circuit simulation and electrostatic field simulation can provide better guidance for optimizing a plasma generator.Finally,the device is used to treat PM2.5 and formaldehyde.The test results show that the degradation rate of PM2.5 can reach 78% after 24 min,and formaldehyde is about 31.5% after 10m in of plasma treatment.展开更多
The mechanisms of streamer generation and propagation in double-sided pulsed surface dielectric barrier discharge(SDBD)on both sides have been analyzed and investigated by experiment and numerical simulation.The fully...The mechanisms of streamer generation and propagation in double-sided pulsed surface dielectric barrier discharge(SDBD)on both sides have been analyzed and investigated by experiment and numerical simulation.The fully exposed asymmetric SDBD has two discharge processes located on the high voltage electrode(HVE)side and the ground electrode(GE)side.Discharge images of the HVE side and GE side are taken by a digital camera under continuous pulse and ICCD(Intensified Charge Coupled Device)is utilized to diagnose the generation and propagation of streamers in single pulse discharge.In order to understand the physical mechanisms of streamer evolution more deeply,we establish a 2D simulation model and analyze it from the aspects of electron density,ion density,reduced electric field and electron impact ionization source term.The results show that the primary and secondary discharges on the HVE side and the GE side of the double-sided SDBD are composed of positive streamer and negative streamer,respectively.On the HVE side,the accumulation of positive charges on the dielectric surface causes the direction of the electric field to reverse,which is the principal factor for the polarity reversal of the streamer.On the GE side,both the negative charges accumulated on the dielectric surface and the falling voltage are the key factors for the streamer polarity switch.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.51325704,51577158, 51607147,and U1234202)
文摘Active flow control based on surface dielectric barrier discharge（SDBD） has become a focus of research in recent years,due to its unique advantages and diverse potential applications.Compared with the conventional SDBD with straight electrodes,the serrated electrode-based SDBD has a great advantage due to its 3D flow topology.It is believed that the boundary layer separation of moving objects can be controlled more effectively with this new type of SDBD.In SDBD with a serrated electrode,the R（tip sharpness） and N（tip number per unit length） have a great influence on the discharge and induced airflow characteristics.In this paper,a parametric study of the characteristics of SDBD with a serrated electrode has been conducted with different ranges of R and N.Aspects of the power consumption,the steady medium temperature distribution,and the maximum induced airflow velocity have been investigated.The results indicate that there is a critical value of R and N where the maximum power consumption and induced airflow velocity are achieved.The uniformity of the steady temperature distribution of the medium surface is found to be more dependent on N.We found that the accelerating effects of the induced airflow can be evaluated with the Schlieren technique,which agree well with the results from the pitot tube.
基金supported by the National Natural Science Foundation of China(60906053,61204069,61274118,61306144,61504079,and 11605112)Scientific and Innovative Action Plan of Shanghai(15DZ1160800 and 17XD1702400)China Postdoctoral Science Foundation(2016 M601595).
文摘Improving energy efficiency in plasma NO removal is a critical issue.When the surface dielectric barrier discharge(SDBD)device is considered as a combination of multiple plasma actuators,the induced plasma aerodynamic effect cannot be ignored,which can affect the mass transfer,then affect the chemical reactions.Five SDBD devices with different electrode arrangements are studied for NO conversion.They correspond to different flow patterns.We find that the energy efficiency in an SDBD device with a common structure(Type 1)is 28%lower than that in SDBD devices with a special arrangement(Types 2–5).Two reasons may explain the results.First,fewer active species are produced in Type 1 because the development of discharge is hindered by the mutually exclusive electric field forces caused by the symmetrically distributed charged particles.Second,the plasma wind induced by the plasma actuator can enhance the mass and heat transfer.The mixing of reactants and products is better in Types 2–5 than Type 1 due to higher turbulence kinetic energy.
基金supported by National Natural Science Foundation of China(No.11175037)National Natural Science Foundation for Young Scientists of China(No.11305017)Special Fund for Theoretical Physics(No.11247239)
文摘The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.
基金supported by National Natural Science Foundation of China under Contract Nos. 11205244, 51076168, 91441123 and 51222701
文摘Flow fields induced by a surface dielectric barrier discharge actuator at low pressure of 7 kPa are measured by particle image velocimetry. The distribution of local vortices in the flow field is revealed by the Q criterion. The reason for the generation of vortices is analyzed and the influence of pulse frequency and duty cycle on vortices is studied. The results show that the Q criterion can reveal the small-scale vortices, which cannot be indicated by the streamline. The direction transition zone where the induced jet moves from the vertical to the tangential and the shear layer between the jet and stationary air are prone to the generation of strong vortices. The influence of pulse frequency on vortices is not obvious, but the variation of duty cycle can significantly affect the strength and distribution of vortices.
基金National Natural Science Foundation of China (No. 11575066).
文摘A surface dielectric barrier discharge (SDBD) can discharge at atmospheric pressure and produce a large area of low-temperature plasma.An SDBD plasma reactor based on the double spiral structure is introduced in this paper.To study the discharge mechanism of SDBD,an equivalent circuit model was proposed based on the analysis of the micro-discharge process of SDBD.Matlab/Simulink is used to simulate and compare the voltage-current waves,Lissajous and discharge power with the experimental results.The consistency of the results verifies the validity of the SDBD equivalent circuit model.Maxwell software based on the finite elements method is used to analyze the electrostatic field distribution of the device,which can better explain the relationship between the discharge image and the electrostatic field distribution.The combination of equivalent circuit simulation and electrostatic field simulation can provide better guidance for optimizing a plasma generator.Finally,the device is used to treat PM2.5 and formaldehyde.The test results show that the degradation rate of PM2.5 can reach 78% after 24 min,and formaldehyde is about 31.5% after 10m in of plasma treatment.
基金supported by National Natural Science Foundation of China(Nos.51877027 and 52107140)Project funded by China Postdoctoral Science Foundation(No.2021M700662)。
文摘The mechanisms of streamer generation and propagation in double-sided pulsed surface dielectric barrier discharge(SDBD)on both sides have been analyzed and investigated by experiment and numerical simulation.The fully exposed asymmetric SDBD has two discharge processes located on the high voltage electrode(HVE)side and the ground electrode(GE)side.Discharge images of the HVE side and GE side are taken by a digital camera under continuous pulse and ICCD(Intensified Charge Coupled Device)is utilized to diagnose the generation and propagation of streamers in single pulse discharge.In order to understand the physical mechanisms of streamer evolution more deeply,we establish a 2D simulation model and analyze it from the aspects of electron density,ion density,reduced electric field and electron impact ionization source term.The results show that the primary and secondary discharges on the HVE side and the GE side of the double-sided SDBD are composed of positive streamer and negative streamer,respectively.On the HVE side,the accumulation of positive charges on the dielectric surface causes the direction of the electric field to reverse,which is the principal factor for the polarity reversal of the streamer.On the GE side,both the negative charges accumulated on the dielectric surface and the falling voltage are the key factors for the streamer polarity switch.
