Investigation of flow control and cooling performance using comb plasma actuators

Abstract

Abstract This paper proposes a novel comb plasma actuator (CPA) for active flow control. The effects of the CPA on the tip and the root are investigated to improve the film cooling effectiveness. Results show that the CPA on the root increases the size of the counter-rotating vortex pairs (CRVPs) and the agminated body force arches the coolant air away from the wall. Nevertheless, the scale of the anti-counter rotating vortex pairs (Anti-CRVPs) induced by CPA on the tip is larger than one of CRVPs, which significantly weakens the coiling effect of the mainstream on the coolant air. The maximum velocity of the near-wall fluid with CPA on the tip is 1.2 times that without a plasma actuator. Compared with plasma off, the wall-averaged film cooling effectiveness increases by 90.9%, 108.9%, 87.2%, and 38.0%, respectively, under blowing ratios of 0.25, 0.5, 0.75, and 1.0 when using CPA on the tip. In addition, the wall-averaged cooling effectiveness increases by 58.7%, 108.9%, and 115.0% when applied voltages are 6 kV, 12 kV, and 24 kV%, respectively. The diffusing body force of CPA on the tip increases coolant air distributions along the spanwise direction. When the blowing ratio increases from 0.25 to 1.0, the spanwise film cooling effectiveness increases by 62.3%, 103.4%, 164.6%, and 150.5%, respectively, on average.