Tubular heat exchange systems

A heat exchange system, comprising:

• a heat exchanger disposed within an inner fan duct of a gas turbine engine and comprising a heat exchanger first flow passage and a heat exchanger second flow passage, the heat exchanger first flow passage coupled to receive engine air from within an engine case of the gas turbine engine, the heat exchanger second flow passage coupled to receive fan air from a bypass flow passage of the gas turbine engine, the heat exchanger configured to transfer heat between the engine air and the fan air;
• wherein the heat exchanger first flow passage comprises an inlet header, a plurality of tubes, and an outlet header, wherein the first fluid flows through the tube in a first direction and wherein the second fluid flows across the tubes in a second flow direction the is perpendicular to the first flow direction, wherein the inlet header and the outlet header each have an arcuate cross-section in a first plane that extends perpendicular to the first flow direction and parallel to the second flow direction, wherein each tube of the plurality of tubes extends linearly between the inlet header and the outlet header and perpendicularly with respect to the first plane, and wherein the plurality of tubes are disposed along an entirety of the arcuate cross-section of the inlet header and the outlet header;
• and
• wherein the inlet header comprises a plurality of header-tube transition portions configured to allow the first fluid to flow from the inlet header and into the tubes, the plurality of header-tube transition portions each comprising a smoothly curved inlet portion and a tapered tube connection portion, wherein the tapered tube connection portion is defined by a first end adjacent to the smoothly curved inlet portion and a second end adjacent to a tube of the plurality of tubes, wherein the first end and second end outer walls define a constant outer diameter, wherein the first end has an inner wall inner diameter that is less than an inner wall inner diameter of the second end such that a radial wall thickness of the first end is greater than a radial wall thickness of the second end, wherein a transition portion between the first end and the second end is defined by an annular wall that extends perpendicularly with respect to the inner walls of the first and second ends, wherein the annular wall has a radial length that is equal to the difference between the inner wall inner diameters of the first and second ends, wherein a lateral end of the tube is disposed abuttingly against the annular wall, an outer wall of the tube is brazed to the inner wall of the second end, and an inner wall of the tube forms a constant inner diameter with the inner wall of the first end.

A heat exchange system, comprising:

• a plurality of heat exchangers disposed within a turbofan engine, each heat exchanger including a heat exchanger first flow passage and a heat exchanger second flow passage, each heat exchanger first flow passage coupled to receive engine air from within an engine case of the turbofan engine, each heat exchanger second flow passage coupled to receive fan air from a bypass flow passage of the turbofan engine, each heat exchanger being configured to transfer heat between the engine air and the fan air;
• wherein the heat exchanger first flow passage comprises an inlet header, a plurality of tubes, and an outlet header, wherein the first fluid flows through the tube in a first direction and wherein the second fluid flows across the tubes in a second flow direction the is perpendicular to the first flow direction, wherein the inlet header and the outlet header each have an arcuate cross-section in a first plane that extends perpendicular to the first flow direction and parallel to the second flow direction, wherein each tube of the plurality of tubes extends linearly between the inlet header and the outlet header and perpendicularly with respect to the first plane, and wherein the plurality of tubes are disposed along an entirety of the arcuate cross-section of the inlet header and the outlet header;
• and
• wherein the inlet header comprises a plurality of header-tube transition portions configured to allow the first fluid to flow from the inlet header and into the tubes, the plurality of header-tube transition portions each comprising a smoothly curved inlet portion and a tapered tube connection portion, wherein the tapered tube connection portion is defined by a first end adjacent to the smoothly curved inlet portion and a second end adjacent to a tube of the plurality of tubes, wherein the first end and second end outer walls define a constant outer diameter, wherein the first end has an inner wall inner diameter that is less than an inner wall inner diameter of the second end such that a radial wall thickness of the first end is greater than a radial wall thickness of the second end, wherein a transition portion between the first end and the second end is defined by an annular wall that extends perpendicularly with respect to the inner walls of the first and second ends, wherein the annular wall has a radial length that is equal to the difference between the inner wall inner diameters of the first and second ends, wherein a lateral end of the tube is disposed abuttingly against the annular wall, an outer wall of the tube is brazed to the inner wall of the second end, and an inner wall of the tube forms a constant inner diameter with the inner wall of the first end.