Film-cooling of cylindrical hole with downstream surface dielectric barrier discharge actuators

Abstract This paper presents a new way to improve film-cooling performance by using surface dielectric barrier discharge actuators installed downstream from film-cooling hole. Results provide insight into the flow field characteristic and film-cooing effectiveness of both primary cylindrical hole with and without actuator, and a comparison is made. The velocity field near the test surface is found to be significantly changed under the effect of actuator, resulting in a new pair of vortexes of which the rotating direction is opposite to that of counter rotating vortex pair. Under the effect of new vortex pair, the trend of hot main flow pushing jet flow up is impeded and the jet flow is induced to flow along spanwise direction. A better jet flow adherent performance and greater jet flow coverage are achieved by installing actuator downstream from cylindrical hole than from primary hole, providing an increment in the film-cooing effectiveness. The effects of each location parameter of the actuator on the film-cooling effectiveness are studied in detail. The results indicate that under different blow ratio, the actuator location parameter has various levels of influence on film-cooing effectiveness. This is mainly due to the strength of counter rotating vortex pair in the primary cylindrical hole and the induced ability of surface dielectric barrier discharge actuators.