Abstract: A compact heat exchanger is disclosed for re-circulating bleed air from a combustor into an inlet and/or exhaust of a gas turbine engine. In an embodiment, the heat exchanger may comprise a plurality of airfoils with internal passages that receive bleed air. The bleed air may be forced through outlets in one or a plurality of concentric passages from the internal passage of each airfoil to an internal cavity of each airfoil, and out of micro-holes within a trailing surface of the airfoil. This enables bleed air to be mixed with gas flowing through the airfoils, in close proximity to the compressor or turbine of the gas turbine engine, while providing acoustic noise suppression and low thermal mixing stratification.