Abstract
Shock waves in supersonic flows can be effectively controlled by gas discharge plasmas, and thermal mechanism has gained preliminary consensus in the literature. In the present paper, we try to validate the thermal mechanism of shock wave control by gas discharge plasmas experimentally. Surface dielectric barrier discharge (DBD) plasma and surface arc discharge plasma were selected as representatives of low-temperature cold plasmas with weak thermal effect and low-temperature thermal plasmas with strong thermal effect, respectively. An oblique shock wave from a wedge was controlled by these two types of gas discharge plasmas respectively in a Mach 2.2 wind tunnel. Schlieren photography and gas pressure measurement results demonstrated that the cold DBD plasma had no obvious control effect on the shock wave, but the shock wave structure was distinctly changed by the hot arc discharge plasma. Under test condition of arc discharge power 1.3 kW, the start point of shock wave shifted upstream 4 mm, the shock wave angle decreased 8.6% and its strength weakened 8.8%. Therefore, we conclude that only the low-temperature thermal plasmas with substantial heat energy addition to the supersonic flow field have the control abilities on shock wave. This work will provide more evidence on the thermal mechanism of shock wave control by gas discharge plasmas.