Provided are fluid exchange apparatuses and methods of exchanging fluids between streams. Exemplary fluid exchange apparatus includes a first interleaved pathway with a plurality of first passages, and a second interleaved pathway with a plurality of second passages, in which the plurality of first passages and the plurality of second passages interleave with one another. Exemplary methods include directing a first fluid through a first interleaved pathway of a fluid exchange apparatus and directing a second fluid through a second interleaved pathway of a fluid exchange apparatus. The first fluid may flow from an upstream portion of a first duct into the first interleaved pathway and may discharge into a downstream portion of the second duct. The second fluid may flow from an upstream portion of the second duct into the second interleaved pathway and may discharge into a downstream portion of the first duct.

A triple-flow turbomachine for an aircraft, including a power transmission module including a torque input connected to a turbine shaft, a first torque output of a gearbox connected to a main shaft for rotatably driving a main fan propeller, and a second torque output of a planet gear connected to a secondary shaft for rotatably driving a secondary fan propeller. The planet gear is independent of the gearbox and arranged downstream of the gearbox.

A triple-flow turbomachine for an aircraft, including a power transmission module including a torque input connected to a turbine shaft, a first torque output of a gearbox connected to a main shaft for rotatably driving a main fan propeller, and a second torque output of a planet gear connected to a secondary shaft for rotatably driving a secondary fan propeller. The planet gear is independent of the gearbox and arranged downstream of the gearbox.

Provided are fluid exchange apparatuses and methods of exchanging fluids between streams. Exemplary fluid exchange apparatus includes a first interleaved pathway with a plurality of first passages, and a second interleaved pathway with a plurality of second passages, in which the plurality of first passages and the plurality of second passages interleave with one another. Exemplary methods include directing a first fluid through a first interleaved pathway of a fluid exchange apparatus and directing a second fluid through a second interleaved pathway of a fluid exchange apparatus. The first fluid may flow from an upstream portion of a first duct into the first interleaved pathway and may discharge into a downstream portion of the second duct. The second fluid may flow from an upstream portion of the second duct into the second interleaved pathway and may discharge into a downstream portion of the first duct.

A turboshaft engine includes a core section extending between an inlet and an outlet of the turboshaft engine. The core section includes a compressor, a main combustor, and a main turbine, such that combustion products from the main combustor drives rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. A primary bypass is fluidly connected to the inlet and the outlet. The primary bypass directs a portion of an airflow entering the inlet around the core section to the outlet. A secondary bypass is located in the core section and is configured to divert a portion of a core airflow of the core section around the main combustor and the main turbine to the power turbine.

A turboshaft engine includes a core section extending between an inlet and an outlet of the turboshaft engine. The core section includes a compressor, a main combustor, and a main turbine, such that combustion products from the main combustor drives rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. A primary bypass is fluidly connected to the inlet and the outlet. The primary bypass directs a portion of an airflow entering the inlet around the core section to the outlet. A secondary bypass is located in the core section and is configured to divert a portion of a core airflow of the core section around the main combustor and the main turbine to the power turbine.

A turbomachinery engine can include a fan assembly with a plurality of variable pitch fan blades. The fan blades are configured such that they define a first VPF parameter and a second VPF parameter. The first VPF parameter is defined as the hub-to-tip radius ratio divided by the fan pressure ratio. The second VPF parameter is defined as the bearing spanwise force divided by the fan area. In some instances, the first VPF parameter is within a range of 0.1 to 0.25, and the second VPF parameter is within a range of 2-30 lbf/in.sup.2. In other instances, the first VPF parameter is within a range of 0.1 to 0.4 and the second VPF parameter is within a range of 5.25-30 lbf/in.sup.2. In certain examples, the turbomachinery engine further includes a pitch change mechanism, a vane assembly, a core engine, and a gearbox.

A turbomachinery engine can include a fan assembly with a plurality of variable pitch fan blades. The fan blades are configured such that they define a first VPF parameter and a second VPF parameter. The first VPF parameter is defined as the hub-to-tip radius ratio divided by the fan pressure ratio. The second VPF parameter is defined as the bearing spanwise force divided by the fan area. In some instances, the first VPF parameter is within a range of 0.1 to 0.25, and the second VPF parameter is within a range of 2-30 lbf/in.sup.2. In other instances, the first VPF parameter is within a range of 0.1 to 0.4 and the second VPF parameter is within a range of 5.25-30 lbf/in.sup.2. In certain examples, the turbomachinery engine further includes a pitch change mechanism, a vane assembly, a core engine, and a gearbox.

A turbomachinery engine can include a fan assembly with a plurality of variable pitch fan blades. The fan blades are configured such that they define a first VPF parameter and a second VPF parameter. The first VPF parameter is defined as the hub-to-tip radius ratio divided by the fan pressure ratio. The second VPF parameter is defined as the bearing spanwise force divided by the fan area. In some instances, the first VPF parameter is within a range of 0.1 to 0.25, and the second VPF parameter is within a range of 2-30 lbf/in.sup.2. In other instances, the first VPF parameter is within a range of 0.1 to 0.4 and the second VPF parameter is within a range of 5.25-30 lbf/in.sup.2. In certain examples, the turbomachinery engine further includes a pitch change mechanism, a vane assembly, a core engine, and a gearbox.

A three-stream engine is provided. The three-stream engine includes a fan section, a core engine disposed downstream of the fan section, and a core cowl annularly encasing the core engine and at least partially defining a core duct. A fan cowl is disposed radially outward from the core cowl and annularly encasing at least a portion of the core cowl. The fan cowl at least partially defining an inlet duct and a fan duct. The fan duct and the core duct at least partially co-extending axially on opposite sides of the core cowl. A heat exchanger disposed within the fan duct. The heat exchanger provides for thermal communication between a fluid flowing through fan duct and a motive fluid flowing through the heat exchanger.