A flow diverter for an air separator of a gas turbine includes a cylindrical body configured to fit within a cooling hole of the air separator. One or more air flow vents are defined through and around a partial circumference of the cylindrical body. A bottom panel closes the cylindrical body at one end. A mounting flange surrounds the cylindrical body at an open end and extends radially outward from the cylindrical body. When the flow diverter is installed, air flows through the open end in a radial direction and exits through the air flow vents in an axial direction. The cylindrical body may include a collapsible region that collapses to engage the air separator and prevent the flow diverter from being dislodged. The air separator may additionally or alternately include supplemental cooling holes in a recessed area proximate to its mounting flange.