Patent Description:
<CIT> discloses an aircraft propulsion system according to the preamble of claim <NUM>. <CIT> discloses an aircraft having energy-conserving means.

The present invention provides an aircraft propulsion system as set forth in claim <NUM>.

<FIG> is a schematic view of an example aircraft propulsion system <NUM> disposed within an aircraft structure <NUM>. The aircraft structure <NUM> may be the aircraft fuselage and/or a portion of a wing or other lift generating aircraft structure. A propulsor assembly <NUM> is disposed within the aircraft structure <NUM> and draws an upper boundary layer flow <NUM> along an upper surface <NUM> and a lower boundary layer flow <NUM> from along a lower surface <NUM> into an inlet duct assembly <NUM>. The propulsor assembly <NUM> generates thrust and exhausts the ingested flows <NUM>, <NUM> through an exhaust duct <NUM>.

The inlet duct assembly <NUM> includes an upper inlet duct <NUM> and a lower inlet duct <NUM> that merge into a common inlet duct <NUM> forward of the propulsor assembly <NUM>. An upper inlet opening <NUM> is disposed along the upper surface <NUM> and provides flow communication of the upper boundary layer flow <NUM> into the upper inlet duct <NUM>. A lower inlet opening <NUM> is disposed along the lower surface <NUM> and provides flow communication of the lower boundary layer flow <NUM> to the lower inlet duct <NUM>. The air flows from the upper inlet duct <NUM> and the lower inlet duct <NUM> are merged within the common inlet duct <NUM> and communicated to the propulsor assembly <NUM>. The propulsor assembly <NUM> imparts energy to the inlet flows to generate a propulsive flow that is exhausted through an exhaust outlet <NUM> that is disposed at an aft point of the aircraft structure <NUM>.

Heat exchangers <NUM>, <NUM> are disposed within the inlet duct assembly <NUM> to provide thermal rejection and recovery from any of a plurality of aircraft systems schematically indicated at <NUM>. The aircraft systems <NUM> include hydraulic, electrical, lubrication, cooling air and energy producing systems utilized for operation of the aircraft and the propulsion system <NUM>. It should be appreciated, that although several aircraft systems are disclosed by way of example, any aircraft system that exchanges thermal energy would benefit from this disclosure and is within the scope and contemplation of this disclosure.

It should be appreciated, that the heat exchangers <NUM>, <NUM> introduce a blockage into the diffused shape of inlet duct assembly <NUM>. The blockage provided by the heat exchangers <NUM>, <NUM> provides for a more aggressive diffuser shape without separation of incoming boundary layer airflow. The aggressive diffuser shape, in turn, provides for a shorter duct length than would be otherwise be required to provide desired aerodynamic properties. Moreover, the possible diffuser duct shape provides for expanded possible locations of the inlet ducts, and thereby the propulsion system within the aircraft structure <NUM>.

In one disclosed embodiment, the upper inlet duct <NUM> includes the upper heat exchanger <NUM> disposed forward of the propulsor assembly <NUM>. A lower heat exchanger <NUM> is disposed in the lower inlet duct <NUM> forward of the propulsor assembly <NUM>. Additionally, both the upper heat exchanger <NUM> and the lower heat exchanger <NUM> are disposed forward of the common inlet duct <NUM>.

An aft heat exchanger <NUM> is disposed aft of the propulsor assembly <NUM> within the exhaust duct <NUM>. The aft heat exchanger <NUM> provides for recovery of heat generated from the propulsive flow exhausted through the exhaust duct <NUM>.

Referring to <FIG> and <FIG> with continued reference to <FIG>, a splitter <NUM> is disposed between the upper inlet duct <NUM> and the lower inlet duct <NUM> forward of the common inlet duct <NUM>. The splitter <NUM> mitigates flow separation of the boundary layer flows <NUM>, <NUM> into the common inlet duct <NUM>.

The upper inlet duct <NUM> and the lower inlet duct <NUM> are rectilinear and merge into a curvilinear shaped common inlet duct <NUM>. A lower transition region <NUM> is disposed between the lower inlet duct <NUM> and the common inlet duct <NUM>. An upper transition region <NUM> is provided between the upper inlet duct <NUM> and the common inlet duct <NUM>. The lower and upper transition regions <NUM> include contoured shapes that transition from the rectilinear shapes of the upper and lower inlet duct <NUM>, <NUM> to the curvilinear shape of the common inlet duct <NUM>. The curvilinear shape of the disclosed common inlet duct embodiment ends in a round shape with a diameter <NUM> that corresponds with a diameter <NUM> of the propulsor assembly <NUM>. The diameters <NUM> and <NUM> correspond by either same or of slightly different sizes to accommodate features of the propulsor assembly <NUM>. The diameter <NUM> is that of a fan <NUM> of the propulsor assembly <NUM>.

The exhaust duct <NUM> is rectilinearly shaped and has a width <NUM> and a maximum height <NUM>. The height transitions from the maximum height <NUM> to a reduce height at the exhaust opening <NUM>. The reduced height transition toward the opening <NUM> forms a nozzle for enhancing propulsive thrust.

The propulsor assembly <NUM> is disposed within a propulsor space <NUM> that transitions from the diameter <NUM> to the rectilinearly shaped exhaust duct <NUM>. The specific shape of the propulsor space <NUM> may be of a non-uniform shape to accommodate propulsor assembly installation and/or other features of the aircraft structure <NUM>.

The rectilinear (cross-sectional) shape of the upper inlet duct <NUM> is rectangular with a height <NUM> (<FIG>) and a width <NUM> (<FIG>). The lower inlet duct <NUM> is also rectangular in shape and includes a height <NUM> (<FIG>) and a width <NUM> (<FIG>). In this disclosed example, the width <NUM> of the upper inlet duct <NUM> is the same as the width <NUM> of the lower inlet duct <NUM>.

The height <NUM> of the upper duct <NUM> and the height <NUM> are maximum heights for each duct <NUM>, <NUM>. The minimum height for each of the ducts <NUM>, <NUM> is disposed at corresponding inlet openings <NUM>, <NUM>. The height of each duct <NUM>, <NUM> expands outward from the openings <NUM>, <NUM> toward corresponding maximum heights <NUM> and <NUM>. In one disclosed example, the maximum heights <NUM> and <NUM> are disposed at or near the beginning of corresponding transition regions <NUM>, <NUM>.

The change and transition of height through each of the ducts <NUM>, <NUM> provide a corresponding change in area for the incoming boundary layer flows <NUM>, <NUM>. The changing area over the length of each duct provides for adjusting airflow parameters to improve efficiency of the propulsor assembly <NUM>. The airflow parameters can include pressure, flow velocity, direction as well as any other known airflow conditions that improve propulsive efficiency.

The height <NUM> of the upper inlet duct <NUM> is larger than the height <NUM> of the lower inlet duct <NUM>. The upper inlet duct <NUM> includes a length <NUM> from the opening <NUM> to the beginning of the transition region <NUM>. The lower inlet duct <NUM> includes a length <NUM> between the opening <NUM> and the beginning of the lower transition region <NUM>. The length <NUM> is greater than the length <NUM>. Accordingly, in one example embodiment, the upper inlet duct <NUM> is larger than the lower inlet duct <NUM>. The different sizes between the upper inlet duct <NUM> and the lower inlet duct <NUM> provide for the accommodation of differences in boundary layer flows <NUM>, <NUM> on corresponding upper and lower surfaces <NUM>, <NUM>. Accordingly, it should be appreciated that the relative size of the upper and lower inlet ducts <NUM>, <NUM> may be modified to accommodate application specific requirements and are within the contemplation and scope of this disclosure. The upper and lower inlet ducts <NUM> and <NUM> may be the same size within the scope and contemplation of this disclosure.

The example upper heat exchanger <NUM> fills the upper inlet duct <NUM> such that most if not all air flows through the heat exchanger <NUM>. Similarly, the example lower heat exchanger <NUM> fills the lower inlet duct such that most, if not all air flows through the lower heat exchanger <NUM>. It should be appreciated that the size and configuration of the heat exchangers <NUM>, <NUM> may vary within the scope of this disclosure.

Referring to <FIG>, the example propulsor assembly <NUM> is shown apart from the inlet duct assembly <NUM> and the exhaust duct assembly <NUM>. The propulsor assembly <NUM> includes an electric motor <NUM> that is coupled to drive the fan <NUM> about a fan axis A through a shaft <NUM>. The shaft <NUM> is supported for rotation by bearing assemblies <NUM>. A forward nut <NUM> secures the fan <NUM> to the shaft <NUM>. The fan <NUM> includes a plurality of fan blades <NUM> that drive airflow aft to generate thrust. A forward spinner <NUM> is disposed over the nut <NUM> to provide a clean aerodynamic shape. The electric motor <NUM> is supported by a pylon <NUM> that is connected to a static portion of the aircraft structure <NUM>. An aft faring <NUM> is secured to an aft portion of the electric motor <NUM> to provide an aerodynamic structure of airflow into the exhaust duct <NUM>. A fan exit guide vane assembly <NUM> is disposed axially aft of the fan <NUM> and directs propulsive airflow into the exhaust duct <NUM>. The fan exit guide vane <NUM> may further provide supportive structure for the propulsor assembly <NUM>. The fan exit guide vane <NUM> may include aerodynamically shaped struts that provide a straightening of any airflow exiting the fan <NUM>. Electric power for the electric motor <NUM> may be provided through electric connections routed through the pylon <NUM>. It should be appreciated, that although one example electric propulsor configuration is provided by way of example, other electrically powered propulsor configurations are within the contemplation of this disclosure. Moreover, although an electric propulsor <NUM> is disclosed by way of example, other engine configurations that generate power through combustion may also be utilized within the scope and contemplation of this disclosure.

Referring to <FIG>, with continued further reference to <FIG> and <FIG>, an example propulsor system embodiment <NUM> includes a plurality of propulsor assemblies <NUM> and corresponding individual duct sectors <NUM>. Each of the duct sectors <NUM> are separate from the other duct sectors and correspond with one of the individual propulsor assemblies <NUM>. Each propulsor assembly <NUM> is operable independently such that all of the propulsor assemblies <NUM> may be operated to provide a combined propulsive thrust. Additionally, the propulsor assemblies <NUM> may be operated to provide less than full thrust by operating only some of the propulsor assemblies <NUM> or a subgroup of propulsor assemblies <NUM>.

Each of the propulsor assemblies <NUM> and separate duct sectors <NUM> provide for tailoring of the propulsion system <NUM> to application specific thrust requirements and space constraints. Moreover, the identical configuration for each propulsor assembly <NUM> and each duct sector <NUM> simplifies operation and assembly.

The propulsor space <NUM> defines the within which the propulsor assembly <NUM> is located and includes an outer contoured shape indicated by arrows <NUM>. The contoured shape <NUM> provides for open spaces <NUM> between adjacent propulsor assemblies <NUM>. The open spaces <NUM> may be utilized to route conduits for coupling aircraft systems <NUM>. The open spaces <NUM> may also be utilized to for supportive structures needed to support the propulsor assemblies <NUM>.

Accordingly, the example increases overall engine efficiency by providing for ingestion of boundary layer flow and also provides a tailorable propulsor configuration that is adaptable to different aircraft structures.

Claim 1:
An aircraft propulsion system comprising:
a propulsive fan assembly configured for assembly into an aircraft structure, the propulsive fan assembly including a fan (<NUM>) rotatable about a fan axis;
an inlet duct assembly (<NUM>) configured to be disposed within the aircraft structure, the inlet duct assembly (<NUM>) including an upper inlet duct (<NUM>) with an upper inlet opening (<NUM>) and a lower inlet duct (<NUM>) with a lower inlet opening (<NUM>), wherein the upper inlet duct (<NUM>) and the lower inlet duct (<NUM>) merge into a common inlet duct (<NUM>) forward of the propulsive fan assembly;
an outlet duct (<NUM>) disposed aft of the propulsive fan assembly; and
a splitter (<NUM>) disposed between the upper inlet duct (<NUM>) and the lower inlet duct (<NUM>) forward of the common inlet duct (<NUM>),
characterised in that:
the upper inlet duct (<NUM>) has a rectangular cross-sectional shape having a minimum height disposed at the upper inlet opening (<NUM>), and the height of the upper inlet duct (<NUM>) expands from the upper inlet opening (<NUM>) towards a maximum height (<NUM>) of the upper inlet duct (<NUM>); and
the lower inlet duct (<NUM>) has a rectangular cross-sectional shape having a minimum height disposed at the lower inlet opening (<NUM>), and the height of the lower inlet duct (<NUM>) expands from the lower inlet opening (<NUM>) towards a maximum height (<NUM>) of the lower inlet duct (<NUM>).