US Patent 11530645 Fluid cooler for a gas turbine engine

A fluid cooler for a gas turbine engine comprises an outer tube having an outer tube inlet at a first end of the fluid cooler and an outer tube outlet at a second end of the fluid cooler. A primary axis of the fluid cooler is defined within the outer tube between the first and second ends of the fluid cooler. A plurality of inner tubes extend within the outer tube between the first second ends of the fluid cooler. The inner tubes have a common inner tube inlet and a common inner tube outlet. The inner tubes extend helically about the primary axis. A first group of the inner tubes are disposed at a first radius from the primary axis and a second group of the inner tubes are disposed at a second radius from the primary axis, the second radius different from the first radius.