Effect of rotation and hole arrangement in cold bridge-type impingement cooling systems

Experimental activity has been performed to study different impingement cooling schemes in static and rotating conditions. Geometry replicates a leading-edge cold bridge system, including a radial supply channel and five rows of film-cooling and showerhead holes. Two impingement geometries have been studied, with different numbers of holes and diameters but with equal overall passage area. Reynolds numbers up to 13,800 and rotation numbers up to 0.002 have been investigated (based on an equivalent slot width). Tests have been performed using a novel implementation of transient heat transfer technique, which allows correct replication of the sign of buoyancy forces by flowing ambient temperature air into a preheated test article. Results show that complex interactions occur between the different features of the system, with a particularly strong effect of jet supply condition. Rotation further interacts with these phenomena, generally leading to a slight decrease in heat transfer