When installing a rectangular supply duct, a turning vane is used to?

Using a turning vane in a rectangular supply duct is primarily aimed at maintaining air velocity as it directs the airflow through the duct system. When air is forced to change direction within the duct, particularly at corners or bends, the turning vane promotes a smoother transition of airflow. This design feature helps ensure that the air does not lose speed or experience significant disruptions as it navigates these changes in direction.

By encouraging a more streamlined flow, turning vanes can improve the overall efficiency of the system, minimizing pressure drops that might occur from abrupt turns. While it may also help in reducing some turbulence, its main function is to keep the air moving consistently and effectively through the ductwork, thereby ensuring optimal delivery of conditioned air to the intended spaces.