Study Of Surface Dielectric Barrier Discharge Characteristics Under Nanosecond Pulse Superimposed DC High Voltage

Plasma flow control is a novel active flow control technology and has a wide application prospect in aerospace and other fields.The surface dielectric barrier discharge driven by nanosecond pulse voltage superimposed DC high voltage has shown a unique advantage in flow control,because it has characteristics such as fast response,sufficient bandwidth and real-time control,meanwhile it can produce a large area of low temperature plasma.In this paper,a new type three-electrode structure actuator is adapted to generate nanosecond-pulse surface sliding discharge driven by a DC high voltage and a nanosecond pulse.The research is conducted on the electrical,optical and flow field characteristics of nanosecond-pulse surface sliding discharge.The experiment setup and corresponding diagnostic system are built for surface dielectric barrier discharge driven by a nanosecond pulse and a DC high voltage.The paper studies the effects of power supply parameters,polarity and potential difference between nanosecond pulse and DC on the electrical characteristics and the discharge plasma morphology of nanosecond-pulse surface sliding discharge,which is also compared with the typical two-electrode SDBD.The results show that there is a minimal potential difference threshold to ignite a nanosecond-pulse sliding discharge and this discharge can obtain a large-scale plasmas that can cover the entire electrode gap.Through the calculating analysis of discharge voltage,current and power energy,it is found that the amplitude of the DC voltage has slightly effect on the current through the pulse voltage electrode.Moreover,the power and consumption energy appear a significant increase trend when the nanosecond-pulse surface sliding discharge occurs.And the power and consumption energy are highly affected by the proportion of the pulse voltage.Further research is conducted on characteristics of nanosecond pulse surface sliding discharge with different structure parameters of the three-electrode actuator and its influencing factors.This paper also illustrates the extent of impact of the parameters such as electrode gap,pulse electrode width,electrode thickness,barrier dielectric material and dielectric material thickness on the electrical characteristics,discharge image and discharge mode.The experimental results show that with the various voltage of different electrode gap,there are always three discharge modes for the surface dielectric barrier discharge driven by a nanosecond pulse and a negative DC high voltage : typical SDBD mode,stable surface sliding discharge mode and spark discharge mode.There are optimum electrode gap and electrode width value for nanosecond-pulse surface sliding discharge actuator,and at this optimum state,the actuator can obtain the maximum energy required by flow control with the relative low excitation value.In addition,the optical emission spectroscopy and flow field characteristics of nanosecond-pulse surface sliding discharge are researched by means of emission spectroscopy system and schlieren system.The results show that the emission spectrum intensity of nanosecond-pulse surface sliding discharge exceeds the typical SDBD,and the intensity and rotational temperature increase in accordance with the amplitude of the DC voltage.The nanosecond-pulse surface sliding discharge can generate two circular waves and a plane wave and these three waves propagate at a same speed.And the DC voltage amplitude and repetition frequency have a great influence on the shock wave intensity and the maximum velocity.Furthermore,surface sliding discharge can induce two opposite jets.To sum up,nanosecond-pulse surface sliding discharge can generate large-scale plasmas,and obtain higher energy required by a flow control.Therefore,the study on the characteristics of nanosecond-pulse surface sliding discharge has an important guiding significance to the optimization design of novel three-electrode actuators.