Experimental Study on the Influence of an Extension Tube on the Evolution Process and Characteristic Parameters of a Gliding Arc

Abstract

The influence of the discharge cone size on the characteristic parameters of a rotating gliding arc, e.g., arc length, arc rotation frequency, and regeneration frequency was investigated when the grounding electrode was equipped with an extension tube. In addition, the effect of air flow rate (100~400 standard liter per minute, SLPM) on the characteristic parameters was also studied (with an extension tube, using a No. 5 discharge cone). The results showed that the disturbance of the outlet flow was intense without an extension tube, which led to the occurrence of the short-circuit regeneration of the gliding arc when the discharge gap was small, and the short-circuit regeneration of the gliding arc could be effectively avoided by adding an extension tube at the grounding end. The existence of the extension tube could significantly increase the arc length by up to 140 mm (250 SLPM, No. 3 discharge cone). The arc lengthening was mainly caused by the unilateral extension of the high voltage side, and the arc shape changed from a “C” to an “L” shape. This also reduced the regeneration frequency to one-quarter of the arc regeneration frequency without extending the tube. Without lengthening the tube, the arc could not achieve complete circumferential rotation. The arc distribution in the annular area between the anode and the cathode was discrete, and the arc distribution was extremely uneven. The existence of the extension tube made the arc rotate uniformly, and the maximum rotation frequency was 228 Hz. The influence of the air flow rate on arc length was mainly reflected in the small flow rate range. When the air flow rate was less than 200 SLPM, the arc length increased first, and then decreased with the increase of the air flow rate, reaching the maximum arc length of 143.6 mm at 150 SLPM. The arc frequency was positively correlated with the air flow rate, but the rotation frequency increased faster than the regeneration frequency: when the flow rate was 150 SLPM, the gliding arc rotated one circle in a tensile fracture period; when the flow rate reached 400 SLPM, the gliding arc rotated two circles in a tensile fracture period.