层／湍流等离子体射流的稳定性与三维特性的实验观测研究

EXPERIMENTAL OBSERVATIONS ON THE STABILITY AND THE 3-D CHARACTERISTICS OF LAMINAR/TURBULENT PLASMA JETS

采用普通照相和短时间曝光成像的ICCD照相技术,观测了低于大气压条件下产生的纯氩和氩-氢直流电弧等离子体射流的高温区的瞬时形貌及其变化,结合电弧弧根在阳极表面贴附行为的观测结果,对射流的稳定性与三维特性和弧根行为之间的关联进行了分析。结果表明,层流等离子体射流的高温区长度明显长于湍流射流情形,并且具有很好的轴对称性和时间稳定性;湍流射流的高温区瞬时形貌则表现出明显的三维特征;等离子体射流的三维特性与弧根在阳极表面的贴附行为没有直接的联系。

The high temperature region and its instantaneous characteristics of the pure argon and argon-hydrogen DC arc plasma jets, generated at reduced pressure, have been observed by using a com- mon digital camera and an ICCD camera with short exposure time. Associated with the observation of the are root attachment on the anode surface, the relationship between the jet stability and 3-D char- acteristics and the arc root behavior has been analyzed. The results show that the high temperature region of a laminar plasma jet is much longer than its turbulent counterpart, and with good axial- symmetry and time stability. The instantaneous high temperature region of the turbulent jet shows apparent 3-D characteristics. And there is no obvious dependence between the 3-D characteristics of the plasma jet and the arc-root attachment behavior.