为了研究交流电压波形、交流正半波以及负半波驱动下的一种新型管状介质阻挡放电装置产生电动风的电气特性和风速特性,通过对比不同驱动波形、不同频率下的电流、风速的大小和方向以获得电动风产生的机理。研究结果表明,完整波形的风速远大于半波,这可能是由于积累电荷的作用导致的。积累电荷产生的原因是驱动器介质的等效电容和等离子体的等效电容二者串联,放电结束后两串联电容由于各自所带有的电荷量不同而无法完全释放其积累的电荷。实验中测得正、负半波所产生风的方向相同,一种可能的解释是当驱动电压是正半波时,由于裸露电极是正高压,可以通过电场的作用将等离子体中的电子吸附到电极上并移除,导致等离子体带正净电荷;而负半波时,由于活性电极是负高压,可以很容易的将等离子体中的正离子吸引到电极表面转化为中性粒子,并能向等离子体中注入电子,这些电子在弱场强区与中性粒子结合,从而导致等离子体中负离子的数量多于正离子。由于正、负半波两种情况下数量占多数的离子电性相反,且电场的方向也相反,因此在这两种情况下等离子体受到的电场力方向相同,从而产生了相同方向的风。
Three kinds of voltage waveforms (sinusoidal AC, positive/negative half-wave AC) are applied to a tubular DBD plasma actuator to create electric wind. It is found that the wind speed created by the sinusoidal high voltage is much higher than that of the positive or the negative half-wave voltage. This phenomenon suggests that the sur- face charging significantly affects the wind speed. As equivalent capacities of dielectric and plasma are in series, they can not discharge completely because they have been charged with different amount of charges during the breakdown. Whereas, when the driving voltage is half wave, the electrostatic field built by surface charge has the oppo site direction relative to the external electric field and can not be removed, leading to two-sided negative effects. On one hand, the discharge in the next cycle reduces the wind speed. On the other hand, the total electric field is lower. Therefore, the speed of the generated wind is lower. The situation is rather different in a sinusoidal AC voltage cycle. When the voltage is reversed, the total electric field strengthens. The breakdown occurs at a relative low voltage, and surface charge is removed. So the wind induced by sinusoidal AC voltage is much stronger than that of the half-wave high voltage.