Method of manufacturing heat exchanger cooling passages in aero propulsion structure

A method of forming a heat exchanger in an aero propulsion structure, the method comprising:

• forming a pilot hole in a ramjet/scramjet heat exchange section with an electrical discharge machine (EDM) drill near a heated flow surface of an aero propulsion structure;
• shaping the pilot hole to have an interior fin with a wire EDM to form a cooling passage;
• and
• forming a groove in a surface of at least one end of the ramjet/scramjet heat exchange section that connects openings of all of the cooling passages to form at least a part of an interface channel between the cooling passages.

A method of forming cooling passages in a heat exchanger in an aero propulsion structure, the method comprising:

• machining an inner contour section of a first section of the heat exchanger to form a heated flow surface;
• forming a plurality of pilot holes in the first section of the heat exchanger around and proximate the heated flow surface with an electrical discharge machine (EDM) drill;
• shaping the pilot holes into cooling passages with a wire EDM with at least one of the pilot holes being shaped to have an interior fin for added heat transfer;
• and
• forming an annular groove in a surface of at least one end of the first section of the heat exchanger, the annular groove connecting all openings to the cooling passages, the annular groove configured to be aligned with a second different groove in an end of a second different section of the heat exchanger to form an interface channel.