Numerical Investigation of the Effect of the Cavity on Flow Control of Continuous Pulses Opposing Plasma Synthetic Jets in Hypersonic Flow

Abstract

Pulse opposing plasma synthetic jets (OPSJs) have potential for reducing the drag coefficient of hypersonic airfoils. This paper numerically investigated the effects and flow control mechanisms of a continuous nanosecond pulse OPSJ on the aerodynamic performance of a hypersonic airfoil. The results indicate that a continuous-pulse OPSJ reduces the airfoil drag coefficient by generating diffracted waves to shift the leading-edge shock wave. However, the flow control effectiveness of a pulse OPSJ decreases with the increase of the pulse sequence. The time-averaged lift-to-drag ratio of the airfoil decreased rapidly from 1.11 for the first pulse sequence to 0.94 for the third pulse sequence, followed by a gradual decrease. The thermal accumulation within the cavity triggers a blocking effect, impeding the heat exchange between the cavity and external fluid. This is the primary factor leading to the decreasing flow control effectiveness of continuous-pulse OPSJs. Furthermore, the results suggest that enhancing the mixing effect within the cavity can improve heat transfer between the cavity and the external flow, suppress thermal accumulation, and improve the flow control capability of continuous-pulse OPSJs in hypersonic flows.