Performance enhancement of single dielectric barrier discharge flow control actuators by means of rear linking tunnels on a reference bluff body using CFD

This paper studies drag reduction on a reference bluff body (Ahmed body) with single dielectric barrier discharge (SDBD) actuators, also called plasma actuators, located at different positions on the model’s rear part with a spanwise arrangement. This active actuator modifies the laminar-to-turbulent transition leading to reattachments of separated flows on the body. A reduction of actuator efficiency when increasing velocity is the main limitation of this method. The main aim of this work is to find a solution for this problem by employing passive flow control to improve the SDBD actuators’ efficiency. For this purpose, rear linking tunnels are added to the model as a novel passive flow control. Numerical simulations were performed to determine the best position of the active actuators on the model. The next step is to study the effect of the passive and active flow control on drag reduction and investigating the combination of these methods for improving the active flow control performance at four different freestream velocities (Re ¼ 0.289 106–0.722 106). The positive effect of this combination is noticeable (a 59% increase in the SDBD actuator’s efficiency for Re ¼ 0.722 106), and the non-linear behaviour of this combination leads to high drag reduction of between 13.29% and 17.96% for different Reynolds numbers.