Abstract: A transition of a combustion section of a gas turbine includes a bulge and an exit frame and a channel wall in-between. A flow channel crosses the transition from an upstream end to a downstream end. The transition includes at the outer side of the channel wall an uneven surface with dents and troughs to improve the heat transfer without lowering the stream of cooling air.

Abstract: A porous heat exchanger including a single piece core extending axially is provided. The core defines a first air inlet and a first air outlet for a first fluid, a second air inlet and a second air outlet for a second fluid. The first/second fluid flows into the core from the first/second air inlet through a first/second fluid channel and flows out of the core through the first/second air outlet. The core includes solid material sheets and porous material sheets disposed alternately with the solid material sheets so each porous material sheet has an adjacent solid material sheet on each side defining one of the first fluid channel for a flow of the first fluid or the second fluid channel for a flow of the second fluid. Heat transfer occurs between the first fluid in the first fluid channel and the second fluid in the second fluid channel.