An aircraft having distributed fans for boundary layer ingestion

Abstract

An aircraft having distributed fans for boundary layer ingestion is provided. In one aspect, the aircraft includes a fuselage extending between a forward end and an aft end. The aircraft includes a plurality of boundary layer ingestion fans arranged in an array. Each fan of the array is mounted to and arranged circumferentially about the aft end of the fuselage. The fans are positioned to ingest a boundary layer airflow flowing along the fuselage. At least two fans of the array are different sizes. Each fan of the array of fans is operably coupled with an electric motor. The electric motors are operable to drive their respective fans to generate thrust. The fans of the array are independently controlled in accordance with boundary layer suction requirements of the aircraft.

Description

[0001] Priority information

[0002] This application claims priority to Indian Patent Application No. 202111020362, filed on May 4, 2021. Technical Field

[0003] This topic generally relates to aircraft propulsion systems, and more specifically to aircraft propulsion systems equipped with boundary layer capture capabilities. Background Technology

[0004] Traditional commercial aircraft typically consist of a fuselage, a pair of wings, and a propulsion system that provides thrust. The propulsion system usually includes at least two aircraft engines, such as turbofan jet engines. Each turbofan jet engine is mounted on a corresponding wing of the aircraft, for example, in a suspended position below the wing. This configuration allows the turbofan jet engines to interact with independent free-flowing airflow unaffected by the wings and / or fuselage. This configuration can reduce turbulence in the air entering the inlet of each corresponding turbofan jet engine, which has a positive impact on the aircraft's net thrust.

[0005] However, drag on an aircraft also affects its net thrust. The total drag on an aircraft, including skin friction, form drag, and induced drag, is generally proportional to the difference between the free-flow velocity of the air approaching the aircraft and the average velocity of the wake generated downstream of the aircraft due to drag.

[0006] Therefore, systems have been proposed to counteract the effects of drag on aircraft. For example, some propulsion systems incorporate boundary layer extraction systems. For instance, some propulsion systems include electrically driven fans on the aircraft's tail fin to gain propulsive benefits by extracting airflow from the fuselage boundary layer. Such boundary layer extraction fans can reduce drag on the aircraft, thereby improving the propulsion efficiency of the propulsion system. Further improvements to aircraft propulsion systems incorporating boundary layer extraction systems are welcome in the art. Summary of the Invention

[0007] Aspects and advantages of the invention will be set forth in part in the description which follows, or may be apparent from the description or may be learned by practice of the invention.

[0008] On one hand, an aircraft is provided. The aircraft includes a fuselage extending between a front end and a rear end. The aircraft has a fan array comprising fans mounted to the rear end of the fuselage and arranged circumferentially around the rear end of the fuselage. The fans are positioned to draw in boundary layer airflow flowing along the fuselage. At least two of the fans have different sizes.

[0009] These and other features, aspects, and advantages of the subject matter will be better understood by referring to the following description and the appended claims. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the subject matter and, together with the description, explain the principles of the subject matter. Attached Figure Description

[0010] The complete and practical disclosure of this subject matter, including its best mode, is set forth in the description with reference to the accompanying drawings, wherein:

[0011] Figure 1 A schematic top view of an aircraft according to various exemplary embodiments of the present disclosure is provided;

[0012] Figure 2 supply Figure 1 A side view of the aircraft;

[0013] Figure 3 supply Figure 1 A schematic rear view of the aircraft;

[0014] Figure 4 supply Figure 1 A schematic cross-sectional view of one of the thrusters of an aircraft.

[0015] Figure 5 A schematic rear view of another aircraft according to an exemplary embodiment of this disclosure is provided;

[0016] Figure 6 Provide for running Figure 1 A flowchart of an example control scheme for a propulsion system of an aircraft according to an exemplary embodiment of the present disclosure;

[0017] Figure 7 A flowchart providing an exemplary method for operating an aircraft according to an exemplary embodiment of the present disclosure; and

[0018] Figure 8 An example computing system is provided according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0019] Reference will now be made in detail to the present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Detailed descriptions use numerical and letter names to refer to features in the figures. The same or similar reference numerals in the figures and description have been used to refer to the same or similar parts of the invention.

[0020] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0021] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and specifically to the normal operating posture of the gas turbine engine or vehicle. For example, in the case of a gas turbine engine, "front" refers to the position closer to the engine inlet, while "rear" refers to the position closer to the engine nozzle or exhaust port.

[0022] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid channel. For example, "upstream" refers to the direction from which fluid flows out, and "downstream" refers to the direction from which fluid flows in. However, as used herein, the terms "upstream" and "downstream" can also refer to electric current.

[0023] The singular forms “a,” “one,” and “the” include plural references unless the context clearly specifies otherwise.

[0024] The approximate language used throughout the specification and claims is applied to modify any quantitative expression that may be varied without altering its underlying function. Therefore, values ​​modified by one or more terms, such as “approximately,” “about,” and “substantially,” are not limited to specified precise values. In at least some cases, approximate language may correspond to the precision of the instrument measuring the value, or the precision of the method or machine used to configure or manufacture the component and / or system. For example, approximate language may refer to a range of ten percent.

[0025] Throughout this specification and claims, scope limitations are combined and interchanged, and these scopes are identified and include all subscopes contained herein, unless otherwise indicated by context or language. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0026] Generally, this disclosure relates to an aircraft having distributed fans for boundary layer intake. In one exemplary embodiment, the aircraft includes a fuselage extending between a front end and a rear end. The aircraft includes a fan array comprising a plurality of boundary layer intake fans. Each fan in the fan array is mounted to the rear end of the fuselage and arranged circumferentially around the rear end of the fuselage. The fans are positioned to intake boundary layer airflow flowing along the fuselage, for example, during flight of the aircraft. In other embodiments, the array of boundary layer intake fans may be positioned at any location along the longitudinal length of the aircraft.

[0027] The fans in the array can have different sizes. For example, in some embodiments, at least two fans in the array have different sizes. In some embodiments, the fan array can include three different sizes of fans. Different fan sizes allow for strategic positioning of the fans to draw in boundary layer airflow while minimizing the overall profile of the array. For example, larger fans can be positioned along the circumference of the fuselage, where more boundary layer airflow needs to be drawn in, while smaller fans can be positioned along the circumference of the fuselage, where less boundary layer airflow needs to be drawn in. Furthermore, smaller fans can be used in more compact physical spaces.

[0028] It is worth noting that each fan in the fan array is operatively coupled to a motor. The motor can operate to drive its respective fan to generate thrust. The fans in the array are controlled independently according to the aircraft's boundary layer inflow requirements. For example, one or more processors in the aircraft's computing system can control the power supplied to each motor, so that the thrust output of the fan can be controlled to its respective thrust output, which may be the same or different depending on the boundary layer inflow requirements and the thrust required by the aircraft.

[0029] The aforementioned features allow for an enhanced boundary layer intake propulsion system capable of handling wake profiles associated with both circular and non-circular fuselage cross-sectional shapes. Furthermore, since the fans can be operated by independent motors, they can be independently controlled according to the boundary layer intake requirements. This provides flexibility in reducing aircraft drag while still meeting the aircraft's thrust needs. Additionally, by having relatively small fans within the array, for example, compared to combining relatively large single fans as boundary layer intake fans, fan handling and / or maintenance become easier in the event of fan blade problems or other fan failures. Fans can be ducted using individual fan housings or circumferentially enclosed in an external nacelle. A partition can extend between the fuselage and the external nacelle and can separate adjacent fans in the array. In this respect, fan tip losses can be minimized. Furthermore, the partition can provide mounting structures for one or more fans, among other benefits.

[0030] Now for reference Figure 1 and Figure 2 , Figure 1 A schematic top view of an exemplary aircraft 100 is provided, which may be combined with various embodiments of this disclosure. Figure 2 A side view of the aircraft 100 is provided. For reference, the aircraft 100 defines a longitudinal direction L1 and a lateral direction L2. The lateral direction L2 is perpendicular to the longitudinal direction L1. The aircraft 100 also defines a longitudinal centerline 114 extending through it along the longitudinal direction L1. The aircraft 100 also defines a circumferential direction C. Various components of the aircraft 100 may also be described herein with respect to... Figure 2The vertical direction V is defined as shown. The position or orientation of a component relative to the vertical direction V is considered when the aircraft 100 is in its such position. Figure 2 The position or orientation determined when the vertical position is horizontally oriented as shown. Furthermore, as... Figure 2 As shown, the aircraft 100 is defined by a centerline 115 extending between its front end 116 and rear end 118. As used herein, "centerline" refers to a line extending along the midpoint of the length of the aircraft 100, disregarding attachments to the aircraft 100 (such as wings and stabilizers discussed below). In this regard, the centerline 115 is defined, for example, as... Figure 2 The midpoint between the top and bottom of the fuselage 112 is determined when the aircraft 100 is in a horizontal position.

[0031] As shown in the figure, the aircraft 100 extends, for example, along a longitudinal direction L1 between a front end 116 and a rear end 118. Furthermore, the aircraft 100 includes a fuselage 112 extending longitudinally from the front end 116 to the rear end 118. The aircraft 100 also includes a tail fin 119 at the tail or rear end 118. Additionally, the aircraft 100 includes a pair of wings, comprising a first port wing 120 and a second starboard wing 122. The first wing 120 and the second wing 122 each extend laterally outward from the fuselage 112 relative to a longitudinal centerline 114. The first wing 120 and a portion of the fuselage 112 together define a first side 124 of the aircraft 100, and the second wing 122 and another portion of the fuselage 112 together define a second side 126 of the aircraft 100. In the illustrated embodiment, the first side 124 of the aircraft 100 is configured as the port side of the aircraft 100, and the second side 126 of the aircraft 100 is configured as the starboard side of the aircraft 100. The longitudinal centerline 114 generally divides the aircraft 100 into the first side 124 and the second side 126.

[0032] The aircraft 100 includes various control surfaces. For this embodiment, each wing 120, 122 includes one or more leading-edge flaps 128 and one or more trailing-edge flaps 130. The aircraft 100 also includes, or more specifically, a tail 119 including a vertical stabilizer 132 having a rudder flap 134 for yaw control and a pair of horizontal stabilizers 136, each horizontal stabilizer 136 having an elevator flap 138 for pitch control. The fuselage 112 additionally includes an outer surface or skin 140. It should be understood that in other exemplary embodiments of this disclosure, the aircraft 100 may additionally or alternatively include any other suitable configuration. For example, in other embodiments, the aircraft 100 may include any other control surface configuration or tail arrangement.

[0033] Figure 1 and 2The exemplary aircraft 100 also includes a propulsion system 150. In this embodiment, the propulsion system 150 is a hybrid electric propulsion system. However, in other embodiments, the propulsion system 150 may be another suitable type of propulsion system, such as an all-electric propulsion system.

[0034] As shown in the figure, the propulsion system 150 includes a first primary thruster 160 and a second primary thruster 170 operable to generate thrust. The first primary thruster 160 is mounted underwing to a first wing 120, and the second primary thruster 170 is mounted underwing to a second wing 122. In other example embodiments, one or both of the first primary thruster 160 and the second primary thruster 170 may be mounted to the aircraft 100 in other suitable locations and / or configurations.

[0035] The first primary thruster 160 includes a gas turbine engine 162 and an electric motor 164 operably coupled to the gas turbine engine 162. The electric motor 164 may be a generator, an electric motor, or a combination of generator and electric motor. For this exemplary embodiment, the electric motor 164 is a combination of generator and electric motor. In this way, when operating as a generator, the electric motor 164 can generate electricity when driven by the gas turbine engine 162. When operating as an electric motor, the electric motor 164 can drive or actuate the gas turbine engine 162. Furthermore, for this exemplary embodiment, the gas turbine engine 162 is configured as a turbofan; therefore, the first primary thruster 160 is configured as a hybrid electric turbofan.

[0036] Similarly, the second primary thruster 170 includes a gas turbine engine 172 and an electric motor 174 operably coupled to the gas turbine engine 172. The electric motor 174 may be a generator, an electric motor, or a combination of generator and electric motor. In this exemplary embodiment, the electric motor 174 is a combination of generator and electric motor. In this way, when operating as a generator, the electric motor 174 can generate electricity when driven by the gas turbine engine 172. When operating as an electric motor, the electric motor 174 can drive or actuate the gas turbine engine 172. Furthermore, in this exemplary embodiment, the gas turbine engine 172 is configured as a turbofan; therefore, the second primary thruster 170 is configured as a hybrid electric turbofan.

[0037] The propulsion system 150 also includes a boundary layer intake system 200. Specifically, as will be explained in further detail herein, the boundary layer intake system 200 includes a plurality of thrusters, each having a fan configured to intake and consume air forming the boundary layer on the fuselage 112 of the aircraft 100. The fan intakes the relatively slow-moving boundary layer airflow... Figure 2The arrow BL is schematically represented in the diagram, and it accelerates the air to generate thrust that propels the aircraft 100. As the fan draws in boundary layer airflow, drag on the aircraft 100 decreases, which increases the efficiency of the propulsion system 150. Therefore, the gas turbine engines 162, 172 of the first primary thruster 160 and the second primary thruster 170 require less thrust to achieve a specific airspeed and require less fuel, among other benefits.

[0038] The propulsion system 150 also includes one or more energy storage units 180 electrically connectable to motors 164, 174 and other electrical loads, such as motors operatively coupled to the fan of the boundary layer uptake system 200. The energy storage unit 180 may be configured as one or more batteries, such as one or more lithium-ion batteries, or alternatively, may be configured as any other suitable energy storage device, such as a supercapacitor. For the propulsion system 150 described herein, the one or more energy storage units 180 are configured to store a relatively large amount of electrical energy. For example, in some exemplary embodiments, the energy storage unit 180 may be configured to store at least about fifty kilowatt-hours of power, such as at least about sixty-five kilowatt-hours, such as at least about seventy kilowatt-hours, and up to about one thousand kilowatt-hours.

[0039] The propulsion system 150 also includes a power management system with a controller 182 and a power bus 184. Motors 164 and 174, the energy storage unit 180, the motor associated with the fan of the boundary layer intake system 200, and the controller 182 are each electrically connected to each other via one or more wires 186 of the power bus 184. For example, the power bus 184 may include various switches or other movable power electronic devices to selectively electrically connect various components of the propulsion system 150. Additionally, the power bus 184 may also include power electronic devices, such as inverters, converters, rectifiers, etc., for regulating or converting power within the propulsion system 150.

[0040] Controller 182 is configured to control the power distribution among the various components of propulsion system 150. For example, controller 182 may control the power electronics of power bus 184 to supply power to various components or draw power from various components. For example, controller 182 may control the power electronics of power bus 184 to draw and / or distribute power from one or more energy storage units 180 and / or motors 164, 174, and to supply power to motors associated with fans of boundary layer intake system 200. This is schematically depicted as wires 186 extending through power bus 184 of controller 182.

[0041] The controller 182 may form part of the computing system 190 of the aircraft 100. The computing system 190 of the aircraft 100 may include one or more processors and one or more storage devices contained within one or more computing devices. For example, such as... Figure 1 As shown, the computing system 190 includes a controller 182 and other computing devices, such as computing device 192. The computing system 190 may also include other computing devices, such as an engine controller (not shown). The computing devices of the computing system 190 can be interconnected via a communication network. For example, computing device 192 is located in the cockpit of aircraft 100 and is communicatively connected to the controller 182 of propulsion system 150 via communication link 194 of the communication network. Communication link 194 may include one or more wired or wireless communication links.

[0042] In this embodiment, computing device 192 is configured to receive and process input and / or other information, such as from pilots or other crew members. In this way, as an example, one or more processors of computing device 192 may receive input indicating a need to change the thrust output generated by the thrusters of aircraft 100, and may, in response to such input, cause, for example, controller 182 to control the power of an electric motor associated with the fan of boundary layer intake system 200.

[0043] The controller 182 and other computing devices of the computing system 190 of the aircraft 100 can be referenced below. Figure 8 The exemplary computing device of the described computing system 500 is configured in a substantially similar manner (and can be configured to perform one or more functions of the exemplary method (400) described below).

[0044] The aircraft 100 may also include multiple sensors for sensing various operating conditions associated with the aircraft 100. These multiple sensors are connected via sensor 195. Figure 1 The image is schematically represented. Sensors can be communicatively coupled to one or more computing devices of the computing system 190. For example, the aircraft 100 may include one or more airspeed sensors, temperature sensors, pressure sensors, altitude sensors, weight sensors, sensors for recording environmental conditions, etc. Sensor data can be provided to one or more processors of the computing system 190.

[0045] refer to Figure 3 and Figure 1-2 , Figure 3A schematic rear view of the aircraft 100 is provided, and a plurality of thrusters of the boundary layer acquisition system 200 are depicted. Specifically, for this embodiment, the boundary layer acquisition system 200 includes a first thruster 210, a second thruster 220, a third thruster 230, a fourth thruster 240, and a fifth thruster 250. Each thruster 210, 220, 230, 240, 250 has a fan rotatable about an axis of rotation. Furthermore, for this embodiment, each thruster 210, 220, 230, 240, 250 has an associated motor. Specifically, the first thruster 210 has a fan 212 and a motor 214 operatively coupled thereto. Similarly, the second thruster 220 has a fan 222 and a motor 224 operably connected thereto, the third thruster 230 has a fan 232 and a motor 234 operably connected thereto, the fourth thruster 240 has a fan 242 and a motor 244 operably connected thereto, and the fifth thruster 250 has a fan 252 and a motor 254 operably connected thereto.

[0046] Each of motors 214, 224, 234, 244, and 254 can be an electric motor or a combination of a generator and an electric motor. In this exemplary embodiment, each of motors 214, 224, 234, 244, and 254 is a combination of a generator and an electric motor. Therefore, when operating in drive or motor mode, motors 214, 224, 234, 244, and 254 can drive their respective fans 212, 222, 232, 242, and 252, such that the fan blades of fans 212, 222, 232, 242, and 252 rotate about their respective axes of rotation. In this respect, the plurality of fans 212, 222, 232, 242, and 252 can be electrically driven fans. When operating in generator mode, motors 214, 224, 234, 244, and 254 can generate electricity when driven by their respective fans 212, 222, 232, 242, and 252, for example, during approach and landing. During flight, one or more of motors 214, 224, 234, 244, and 254 may operate in drive or motor mode to power their respective fans 212, 222, 232, 242, and 252, and one or more of motors 214, 224, 234, 244, and 254 may operate in generator mode to generate electricity. In other situations, all motors 214, 224, 234, 244, and 254 may operate in drive or motor mode to power their respective fans 212, 222, 232, 242, and 252. In still other situations, all motors 214, 224, 234, 244, and 254 may operate in generator mode to power their respective fans 212, 222, 232, 242, and 252. For example, the generated electrical energy may be stored in energy storage unit 180 and supplied to one or both of motors 164 and 174, or it may be supplied to other aircraft systems or loads.

[0047] In this embodiment, fans 212, 222, 232, 242, and 252 are mounted to the rear end 118 of the fuselage 112 and together form a distributed fan array 202. As shown in the figure, fans 212, 222, 232, 242, and 252 are arranged circumferentially around the fuselage 112 and positioned such that they draw in boundary layer airflow flowing along the fuselage 112. Figure 3As best shown, for this embodiment, considering the tail configuration, fans 212, 222, 232, 242, and 252 are arranged as far as possible around the entire circumference of fuselage 112, which in this exemplary embodiment has a circular cross-sectional shape. In this respect, the fans 212, 222, 232, 242, and 252 of fan array 202 are arranged around fuselage 112 to capture at least ninety percent (90%) of the boundary layer airflow flowing along fuselage 112. However, in other embodiments, the fans of fan array 202 do not need to be arranged around the entire circumference of fuselage 112. For example, in some embodiments, the fans of fan array 202 are arranged around half the circumference of fuselage 112. Furthermore, in some embodiments, at least a portion of at least one of fans 212, 222, 232, 242, and 252 extends behind the trailing edge of vertical stabilizer 132 of aircraft 100. In other embodiments, at least a portion of each fan 212, 222, 232, 242, 252 extends behind the trailing edge of the vertical stabilizer 132 of the aircraft 100.

[0048] Figure 4 A schematic cross-sectional view of the first thruster 210 of the aircraft 100 is provided. Although the first thruster 210 is referenced... Figure 4 It should be understood, as shown and described, that the other thrusters 220, 230, 240, 250 of the boundary layer uptake system 200 may be configured in the same or similar manner. Therefore, for the sake of brevity, only the first thruster 210 will be described in detail.

[0049] Reference Figure 4 The first thruster 210 includes a fan 212 and a motor 214. The first thruster 210 defines an axial direction A2 extending along a longitudinal centerline axis 211, through which the longitudinal centerline axis 211 extends for reference. In this exemplary embodiment, the longitudinal centerline axis 211 is coaxial with the rotation axis AX1 of the fan 212. Furthermore, the first thruster 210 defines a radial direction R2. For the depicted embodiment, the fan 212 can be rotated about the rotation axis AX1 by the motor 214.

[0050] Fan 212 includes a plurality of fan blades 213 and a fan shaft 215. The plurality of fan blades 213 are attached to / rotate with the fan shaft 215 and are spaced apart generally along the circumferential direction (not shown) of the first thruster 210. In some exemplary embodiments, the plurality of fan blades 213 may be fixedly attached to the fan shaft 215, or alternatively, the plurality of fan blades 213 may be rotatable relative to the fan shaft 215, as in the illustrated embodiment. For example, each of the plurality of fan blades 213 defines a respective pitch axis P2, and in the depicted embodiment, it is attached to the fan shaft 215 such that the pitch of each of the plurality of fan blades 213 can be changed by a pitch changing mechanism 217, for example, uniformly. Changing the pitch of the plurality of fan blades 213 can increase the efficiency of the first thruster 210 and / or can allow the first thruster 210 to achieve a desired thrust distribution. For such exemplary embodiments, fan 212 may be referred to as a variable-pitch fan. In other exemplary embodiments, the fan blades 213 may be fixed and therefore not pitched.

[0051] Furthermore, in the depicted embodiment, the first thruster 210 includes a fan housing 218 attached to the core 219 of the first thruster 210 via one or more struts or outlet guide vanes 204. The outlet guide vanes 204 are positioned downstream of the fan blades 213. Additionally, the first thruster 210 may include an inlet guide vane 206. The inlet guide vane 206 is positioned upstream of the fan blades 213. The inlet guide vane 206 may be shaped and / or oriented to guide and / or modulate airflow (e.g., boundary layer airflow) into the fan 212 to, for example, increase the efficiency of the fan 212 or reduce distortion of the airflow therein. In some embodiments, the inlet guide vane 206 may be configured as a fixed inlet guide vane extending between the fan housing 218 and the core 219. Alternatively, as in this exemplary embodiment, the inlet guide vane 206 may be configured as a variable inlet guide vane. In this regard, the inlet guide vanes 206 can pitch about their respective pitch axes to control the incoming airflow, for example along the fuselage 112 ( Figure 1 ) The flowing boundary layer airflow.

[0052] Furthermore, in this embodiment, the fan housing 218 completely surrounds the fan 212, particularly the plurality of fan blades 213. Therefore, in this embodiment, the fan 212 can be referred to as a duct fan. In some embodiments, reference is also made to... Figure 3All fans 212, 222, 232, 242, and 252 are fully ducted. However, in other embodiments, at least one fan of fan array 202 is fully ducted, meaning the fan blades are completely or annularly enclosed within a fan housing or nacelle. In other embodiments, at least one fan of fan array 202 is partially ducted, meaning the fan blades are partially enclosed within a fan housing or nacelle. In some embodiments, all fans of fan array 202 are partially ducted. In some further embodiments, at least one of the fans is non-ducted, meaning it is not enclosed within a fan housing or nacelle. For example, in some embodiments, all fans of fan array 202 are non-ducted.

[0053] Especially refer to Figure 4 The fan shaft 215 is mechanically connected to the motor 214 within the core 219, such that the motor 214 drives the fan 212 via the fan shaft 215. The fan shaft 215 is supported by one or more bearings 208, such as one or more roller bearings, ball bearings, or any other suitable bearings. Furthermore, the motor 214 can be an inner rotor motor (i.e., including a rotor positioned radially inside the stator), or it can be an outer rotor motor (i.e., including a stator positioned radially inside the rotor), or alternatively, it can still be an axial flux motor (i.e., the rotor is neither outside nor inside the stator, but offset from it along the motor's axis).

[0054] As described above, a power source (e.g., one or more of motors 164, 174 or one or more of energy storage units 180) is electrically connected to motor 214 to provide power thereto. More specifically, motor 214 is electrically connected to the power source via power bus 184, and even more specifically, via one or more cables or wires 186 extending therethrough.

[0055] Refer again Figures 1 to 3 At least two fans of fan array 202 are primarily positioned above the centerline 115, and at least two fans of fan array 202 are primarily positioned below the centerline 115, for example, along the vertical direction V. Specifically, in this embodiment, fan 212 of the first thruster 210 and fan 222 of the second thruster 220 are primarily positioned above the centerline 115. Therefore, at least two fans of fan array 202 are primarily positioned above the centerline 115. In fact, as... Figure 3 Ideally, fans 212 and 222 are positioned completely above the centerline 115, for example, along the vertical direction V.

[0056] Furthermore, in this embodiment, the fan 232 of the third thruster 230, the fan 242 of the fourth thruster 240, and the fan 252 of the fifth thruster 250 are primarily positioned below the centerline 115, for example, along the vertical direction V. Therefore, at least two fans of the fan array 202 are primarily positioned below the centerline 115. In fact, as... Figure 3 As shown, fans 232, 242, and 252 are positioned completely below the centerline 115, for example, along the vertical direction V. Furthermore, as shown, the fan 252 of the fifth thruster 250 is positioned between the fan 232 of the third thruster 230 and the fan 242 of the fourth thruster 240. Along the lateral direction L2, the rotation axis AX5 of the fifth fan 252 is aligned with the longitudinal centerline 114 of the aircraft 100.

[0057] As used herein, "primarily" means that 50% or more of the disk defined by a given fan is positioned above or below the object in the vertical direction V. The disk associated with the fan is the area swept out by the fan during operation. For example, in the case where the fan radius R extends from the tip of one of the blades to the fan's axis of rotation, the disk can be defined by A = πR. 2 Given that A is the area of ​​the disk.

[0058] Furthermore, in this embodiment, at least one fan primarily positioned above the centerline 115 is positioned along the lateral direction L2 on the first side 124 of the aircraft 100, and at least one fan primarily positioned above the centerline 115 is positioned along the lateral direction L2 on the second side 126 of the aircraft 100. Specifically, as... Figure 3 As shown, the fan 212 of the first thruster 210 is positioned along the lateral direction L2 on the first side 124 of the aircraft 100, while the fan 222 of the second thruster 220 is positioned along the lateral direction L2 on the second side 126 of the aircraft 100. Furthermore, in this embodiment, at least one fan primarily positioned below the centerline 115 is positioned along the lateral direction L2 on the first side 124 of the aircraft 100, and at least one fan primarily positioned below the centerline 115 is positioned along the lateral direction L2 on the second side 124 of the aircraft 100. Figure 3 As shown, the fan 232 of the third thruster 230 is positioned along the lateral direction L2 on the first side 124 of the aircraft 100, and the fan 242 of the fourth thruster 240 is positioned along the lateral direction L2 on the second side 126 of the aircraft 100.

[0059] As further described, the fans 212, 222, 232, 242, and 252 of the fan array 202 are surrounded by an outer nacelle 260. The outer nacelle 260 may be a single annular component or may be segmented. For example, the outer nacelle 260 may include: a first segment that surrounds the fan 212 and spans between the vertical stabilizer 132 and the horizontal stabilizer 136 extending from the fuselage 112 at a first side 124; a second segment that surrounds the fan 222 and spans between the vertical stabilizer 132 and the horizontal stabilizer 136 extending from the fuselage 112 at a second side 126; and a third segment that surrounds the fans 232, 242, and 252 and spans between the horizontal stabilizer 136 extending from the fuselage 112 at a first side 124 and the horizontal stabilizer 136 extending from the fuselage 112 at a second side 126.

[0060] like Figure 2 Ideally, the outer nacelle 260 extends between the leading edge 262 and the trailing edge 264, for example, along the longitudinal direction L1. Figure 3 As best shown, one or more partition walls may extend between the fuselage 112 and the outer nacelle 260. Each partition wall may separate adjacent fans of the fan array 202. For example, in this exemplary embodiment, a first partition wall 270 extends between the fuselage 112 and the outer nacelle 260 and separates or isolates the fan 232 of the third thruster 230 from the fan 252 of the fifth thruster 250. Additionally, a second partition wall 272 extends between the fuselage 112 and the outer nacelle 260 and separates or isolates the fan 242 of the fourth thruster 240 from the fan 252 of the fifth thruster 250. The first partition wall 270 and the second partition wall 272 may advantageously provide mounting structures for the fan housings of the fans 232, 242, 252 and may minimize losses from the fan blade tips, for example, by directing airflow generally rearward in the longitudinal direction L1 rather than towards another fan.

[0061] Generally, the first partition wall 270 extends outward from the fuselage 112 in a plane orthogonal to the circumferential direction C. In this respect, the first partition wall 270 extends radially outward from the fuselage 112 relative to the longitudinal centerline 114, and the first partition wall 270 also extends axially or along the longitudinal direction L1 of the aircraft 100. Figure 1 and 2 The first partition wall 270 extends from the fuselage 112 at its proximal end and from the outer cabin 260 at its distal end. In this respect, the first partition wall 270 connects the fuselage 112 and the outer cabin 260.

[0062] Furthermore, as described above, the first partition wall 270 extends axially or along the longitudinal direction L1. More specifically, the first partition wall 270 may extend between a leading edge and a trailing edge, for example, along the axial or longitudinal direction L1. In some embodiments, the first partition wall 270 may extend the entire axial or longitudinal length of the outer nacelle 260, i.e., from the leading edge 262 to the trailing edge 264 of the outer nacelle 260. In other embodiments, the first partition wall 270 may extend less than the entire axial or longitudinal length of the outer nacelle 260. For example, in some embodiments, the leading edge of the first partition wall 270 may be aligned with or positioned behind the leading edge of the fan housing of at least one of the fans 232, 252 along the longitudinal direction L1, wherein the fan housing of at least one fan is positioned behind the leading edge 262 of the outer nacelle 260 along the longitudinal direction L1. Furthermore, in such an embodiment, the trailing edge of the first partition wall 270 may be positioned along the longitudinal direction L1 in front of or behind or aligned with the trailing edge of the fan housing of at least one of the fans 232, 252, wherein the trailing edge of the fan housing of the at least one fan may be positioned along the longitudinal direction L1 in front of or behind or aligned with the trailing edge 264 of the outer nacelle 260.

[0063] Similar to the first partition wall 270, the second partition wall 272 extends outward from the fuselage 112 in a plane orthogonal to the circumferential direction C. In this respect, the second partition wall 272 extends radially outward from the fuselage 112 relative to the longitudinal centerline 114, and also axially or along the longitudinal direction L1 of the aircraft 100. Figure 1 and 2 The second partition wall 272 extends from the first partition wall 270. Its proximal end is connected to the fuselage 112 and its distal end is connected to the outer nacelle 260. The second partition wall 272 is circumferentially spaced from the first partition wall 270.

[0064] Furthermore, as noted, the second partition wall 272 extends axially or along the longitudinal direction L1. More specifically, the second partition wall 272 may extend between a leading edge and a trailing edge, for example, along the axial or longitudinal direction L1. In some embodiments, the second partition wall 272 may extend the entire axial or longitudinal length of the outer nacelle 260, i.e., from the leading edge 262 to the trailing edge 264 of the outer nacelle 260. In other embodiments, the second partition wall 272 may extend less than the entire axial or longitudinal length of the outer nacelle 260. For example, in some embodiments, the leading edge of the second partition wall 272 may be aligned with or positioned behind the leading edge of the fan housing of at least one of the fans 242, 252 along the longitudinal direction L1, wherein the fan housing of at least one fan is positioned behind the leading edge 262 of the outer nacelle 260 along the longitudinal direction L1. Furthermore, in such an embodiment, the rear edge of the second partition wall 272 may be positioned in the longitudinal direction L1 in front of or behind or aligned with the rear edge of the fan housing of at least one of the fans 242, 252, wherein the rear edge of the fan housing of the at least one fan may be positioned in the longitudinal direction L1 in front of or behind or aligned with the rear edge 264 of the outer nacelle 260.

[0065] like Figure 3 As shown, the fan housing of fan 252 can be connected to and supported by the first partition wall 270, the second partition wall 272, and the outer nacelle 260. The fan housing of fan 232 can be connected to and supported by the first partition wall 270, the outer nacelle 260, and, in this embodiment, the horizontal stabilizer 136 extending from the fuselage 112 on the first side 124. The fan housing of fan 242 can be connected to and supported by the second partition wall 272, the outer nacelle 260, and, in this embodiment, the horizontal stabilizer 136 extending from the fuselage 112 on the second side 126. In this respect, each of fans 232, 242, and 252 is supported by at least three structures.

[0066] The fan housing of fan 212 can be connected to and supported by the horizontal stabilizer 136, the outer nacelle 260, and the vertical stabilizer 132 extending from the fuselage 112 on the first side 124. The fan housing of fan 222 can be connected to and supported by the horizontal stabilizer 136, the outer nacelle 260, and the vertical stabilizer 132 extending from the fuselage 112 on the second side 126. In this respect, fans 212 and 222 are each supported by at least three structural supports.

[0067] In some alternative embodiments, the boundary layer intake system 200 does not need to include a partition wall. In such alternative embodiments, one or more outlet guide vanes of each fan of the fan array 202 may extend through their respective fan housings and connect the fans to the fuselage 112, and one or more outlet guide vanes of each fan of the fan array 202 may extend through their respective fan housings and connect the fans to the outer nacelle 260. In other exemplary embodiments, the boundary layer intake system 200 does not need to include the outer nacelle 260. In such embodiments, for example, one or more outlet guide vanes of each fan of the fan array 202 may extend through their respective fan housings and connect the fans to the fuselage 112.

[0068] In addition, such as Figure 3 As best shown, fan array 202 includes at least two fans of different sizes. Specifically, for this embodiment, fan array 202 includes at least three fans of different sizes. As shown, fan 252 of the fifth thruster 250 is the largest fan in fan array 202, as measured by the distance from the rotation axis AX5 to the tip of one of the fan blades of fan 252. Fans 212 and 222 of the first and second thrusters 210 and 220 are of the same size but smaller than fan 252 of the fifth thruster 250. Fans 232 and 242 of the third and fourth thrusters 230 and 240 are of the same size but smaller than fans 212 and 222 of the first and second thrusters 210 and 220. In this respect, fans 232 and 242 of the third and fourth thrusters 230 and 240 are smaller than fan 252 of the fifth thruster 250. Therefore, in this exemplary embodiment, fan array 202 includes at least three fans of different sizes. The size of each fan is measured by the distance from its axis of rotation to the tip of one of its fan blades. By using fans of different sizes in the fan array 202, the fans can be more cleverly arranged to capture boundary layer airflow, despite the configuration of the tail fin 119 (which includes the vertical stabilizer 132 and the horizontal stabilizer 136 in this embodiment) and the shape of the fuselage 112.

[0069] Figure 5 A schematic rear view of another aircraft 100 according to an exemplary embodiment of the present disclosure is provided. As shown, for this embodiment, the fuselage 112 has a non-circular cross-sectional shape. In particular, for this embodiment, the fuselage 112 has a rectangular shape with curved edges. Furthermore, as... Figure 5 As shown, the propulsion system includes a boundary layer intake system 200, which is operable to take in boundary layer airflow flowing along the fuselage 112, although its cross-sectional shape is non-circular.

[0070] As described, for Figure 5In one embodiment, the boundary layer capture system 200 includes a first thruster 310, a second thruster 320, a third thruster 330, a fourth thruster 340, a fifth thruster 350, a sixth thruster 360, a seventh thruster 370, an eighth thruster 380, and a ninth thruster 390. Each thruster 310, 320, 330, 340, 350, 360, 370, 380, and 390 has a fan rotatable about a rotational axis. Furthermore, in this embodiment, each thruster 310, 320, 330, 340, 350, 360, 370, 380, and 390 has an associated motor.

[0071] Specifically, the first thruster 310 has a fan 312 and a motor 314 operably connected thereto. Similarly, the second thruster 320 has a fan 322 and a motor 324 operably connected thereto, the third thruster 330 has a fan 332 and a motor 334 operably connected thereto, the fourth thruster 340 has a fan 342 and a motor 344 operably connected thereto, the fifth thruster 350 has a fan 352 and a motor 354 operably connected thereto, the sixth thruster 360 has a fan 362 and a motor 364 operably connected thereto, the seventh thruster 370 has a fan 372 and a motor 374 operably connected thereto, the eighth thruster 380 has a fan 382 and a motor 384 operably connected thereto, and the ninth thruster 390 has a fan 392 and a motor 394 operably connected thereto. Thrusters 310, 320, 330, 340, 350, 360, 370, 380, and 390 can be configured as described above.

[0072] In this embodiment, the fans of the fan array 302, primarily positioned above the centerline 115, are organized into a first group 304 and a second group 306. As shown, the fans in the first group 304 include fans 312, 322, and 332, and the fans in the second group 306 include fans 342, 352, and 362. In this respect, the first group 304 includes at least three fans, and the second group 306 includes at least three fans. Furthermore, the fans 312, 322, and 332 of the first group 304 are positioned along the lateral direction L2 on the first side 124 of the aircraft 100, while the fans 342, 352, and 362 of the second group 306 are positioned along the lateral direction L2 on the second side 126 of the aircraft 100.

[0073] In addition, for Figure 5 In the illustrated embodiment, at least one fan, primarily positioned below the centerline 115, is positioned laterally along the L2 direction on a first side 124 of the aircraft 100, and at least one fan, primarily positioned below the centerline 115, is positioned laterally along the L2 direction on a second side 126 of the aircraft 100. Figure 5As shown, the fan 372 of the seventh thruster 370 is positioned along the lateral direction L2 on the first side 124 of the aircraft 100, and the fan 382 of the eighth thruster 380 is positioned along the lateral direction L2 on the second side 126 of the aircraft 100.

[0074] In addition, such as Figure 5 As best shown, the fans in fan array 302 have different sizes. Specifically, for this embodiment, fan array 302 includes at least four different sizes of fans. As shown, fans 312, 332, 342, and 362 are all of the first size. Fans 322 and 352 are both of the second size, which is larger than the first size. Fans 372 and 382 are both of the third size, which is larger than the second size. Fan 392 is of the fourth size, which is larger than the third size. The size of each fan is measured by the distance from its axis of rotation to the tip of one of its fan blades. By using fans of different sizes in fan array 302, the fans can be more cleverly arranged to capture boundary layer airflow, despite the configuration of tail fin 119 (which includes vertical stabilizer 132 and horizontal stabilizer 136 in this embodiment) and the non-circular shape of fuselage 112.

[0075] Furthermore, in this embodiment, each fan is separated from adjacent fans by a partition wall extending between the fuselage 112 and the outer nacelle 260. The partition wall can be similarly constructed as described above. Figure 3 The partition walls of this embodiment are as follows. In this embodiment, a first partition wall 315 extends between the fuselage 112 and the outer cabin 260 and separates fan 312 and fan 322. A second partition wall 325 extends between the fuselage 112 and the outer cabin 260 and separates fan 322 and fan 332. A third partition wall 335 extends between the fuselage 112 and the outer cabin 260 and separates fan 342 and fan 352. A fourth partition wall 345 extends between the fuselage 112 and the outer cabin 260 and separates fan 352 and fan 362. A fifth partition wall 355 extends between the fuselage 112 and the outer cabin 260 and separates fan 372 and fan 392. A sixth partition wall 365 extends between the fuselage 112 and the outer cabin 260 and separates fan 382 and fan 392. The partition walls 315, 325, 335, 345, 355, and 365 can advantageously provide a mounting structure for the fan housing of the fan array 302 and can minimize the loss of the fan blade tips, for example, by guiding the airflow approximately backward in the longitudinal direction L1 rather than towards another fan.

[0076] Now return to Figure 1 , 23. Notably, at least two fans of fan array 202 can be controlled independently of each other. For example, one or more processors of computing system 190 can be configured to independently control the thrust output of at least two fans of fan array 202. As an example, computing system 190 can be configured to independently control the thrust output of fan 212 of first thruster 210 and fan 222 of second thruster 220, such that they produce their respective thrust outputs, which may be the same or different. In this regard, at least two fans of fan array 202 can be controlled independently, for example, according to the requirements of boundary layer intake, as will be further explained below. This can ultimately optimize the reduction of drag on aircraft 100 while still allowing propulsion system 150 to meet the required thrust of aircraft 100.

[0077] In some embodiments, more than two fans of the fan array 202 can be controlled independently. For example, in such embodiments, each fan 212, 222, 232, 242, 252 of the fan array 202 can be controlled independently. Specifically, one or more processors of the computing system 190 can be configured to control the thrust output of each fan of the fan array 202 independently. For example, the computing system 190 can be configured to control the thrust output of fans 212, 222, 232, 242, 252 independently, such that they produce their own thrust outputs, which may be the same or different. This provides flexibility in reducing drag on the aircraft 100 while still meeting the aircraft 100's required thrust requirements, among other benefits.

[0078] For example, refer to Figures 1 to 3 and Figure 6 When independently controlling the thrust output of at least two fans of fan array 202, one or more processors of computing system 190 may be configured to receive data 280 indicating one or more operating conditions associated with aircraft 100. Operating conditions may include, but are not limited to, environmental conditions (e.g., ambient air temperature, humidity, wind conditions, air pressure, weather conditions, etc.), airspeed of aircraft 100, altitude of aircraft 100, health status of one or more fans of fan array 202, health status of one or more primary thrusters 160, 170 (or components thereof), electrical load of aircraft 100, and / or current power required by the system.

[0079] Furthermore, it should be noted that in some embodiments, data 280 indicating one or more operating conditions associated with aircraft 100 may include the sensed or derived boundary layer airflow velocity at each of at least two independently controllable fans of fan array 202. In some cases, particularly where each fan of fan array 202 is independently controllable, data 280 indicating one or more operating conditions associated with aircraft 100 may include the sensed or derived boundary layer airflow velocity at each fan of fan array 202. For example, sensors may be placed at or near each fan of fan array 202. Depending on the sensor's location, the sensor may sense the local velocity of the boundary layer airflow flowing into, through, or out of the fans of fan array 202. The sensed sensor data may be provided to one or more processors of computing system 190. Raw sensed data may be received as part of data 280, or derived values ​​based on sensed data may be received as part of data 280. In some embodiments, the local velocity of the boundary layer airflow flowing into, through, or out of the fans of fan array 202 may be derived from other sensed parameters, such as the airspeed, altitude, and environmental conditions of aircraft 100.

[0080] Using the received data 280, one or more processors of the computing system 190 can be configured to determine a boundary layer ingestion requirement 282 for each fan in the fan array 202, the fans of the fan array 202 being independently controlled at least in part based on the data 280. The boundary layer ingestion requirement 282 can be determined as a value corresponding to the thrust output required by the fan to optimally reduce drag along the fuselage 112 of the aircraft 100 at a local location associated with the given fan. The boundary layer ingestion requirement 282 for a given fan can be determined at least in part based on local velocity and environmental conditions at the given fan, as well as other possible operating conditions.

[0081] For example, in an embodiment where at least two fans of fan array 202 are controlled independently, one or more processors of computing system 190 can determine a boundary layer intake requirement 282 for each of the at least two fans, at least in part, based on data 280. In this way, the thrust output of at least two fans of the fan array can be independently controlled to their respective thrust output, at least in part, based on their respective boundary layer intake requirements 282.

[0082] Specifically, based at least in part on the boundary layer ingestion requirement 282 determined for each of the at least two fans by data 280, one or more processors of the computing system can generate one or more instructions 284. When executed, the one or more instructions 284 can cause one or more controllable devices of the aircraft 100 to supply power to the motors associated with the at least two fans, such that the fans meet their respective boundary layer ingestion requirements 282.

[0083] For example, suppose that the fan 212 of the first thruster and the fan 222 of the second thruster 220 are controlled independently. One or more processors of controller 182 may, based on one or more generated instructions 284 (which are generated based on the boundary layer intake requirement 282 determined for fan 212), cause components of power bus 184 (e.g., one or more switching devices of power converters) to supply power to motor 214 from one or more energy storage units 180, motor 164 and / or motor 174, thereby controlling fan 212 to a first speed. Similarly, one or more processors of controller 182 may, based on one or more generated instructions 284 (which are generated based on the boundary layer intake requirement 282 determined for fan 222), cause components of power bus 184 to supply power to motor 214 from one or more energy storage units 180, motor 164 and / or motor 174, thereby controlling fan 222 to a second speed, wherein the first speed and the second speed may be the same or different speeds.

[0084] In cases where fans other than 212 and 222 are to be controlled independently, one or more processors of controller 182 can, based on one or more generated instructions 284, cause components of power bus 184 to supply power from one or more energy storage units 180, motor 164, and / or motor 174 to their respective motors, such that the fans are controlled to their respective speeds, which may be the same or different from each other. In this regard, when controlling the thrust output of the fans in the fan array 202 to be controlled independently, the fans are controlled to their respective speeds. Controlling the fan thrust output, or in this example, controlling the fan speed, allows the incoming boundary layer airflow to be locally accelerated at different rates according to local boundary layer intake requirements.

[0085] In some embodiments, in addition to independently controlling the rotational speed of the fans in the fan array 202 to control their respective thrust output, or alternatively, the pitch of the inlet guide vanes of the fans can be independently controlled to control the thrust output of the fans. Specifically, when controlling the thrust output of at least two fans in the fan array 202 independently, the inlet guide vanes of the first fan and the second fan of the at least two fans can be independently controlled to their respective pitch positions. In this way, the incoming boundary layer airflow can be locally accelerated at different rates according to local boundary layer intake requirements.

[0086] Furthermore, in some embodiments, in addition to independently controlling the rotational speed of the fans in the fan array 202 to control their respective thrust output, or alternatively, independently controlling the pitch of the fan blades to control the output of the thrust fans. Specifically, when independently controlling the thrust output of at least two fans in the fan array 202, the fan blades of the first fan and the fan blades of the second fan can be independently controlled to their respective pitch positions. In this way, the incoming boundary layer airflow can be locally accelerated at different rates according to local boundary layer intake requirements.

[0087] Figure 7 A flowchart is provided for an exemplary method (400) of operating an aircraft with a boundary layer take-up system according to an exemplary embodiment of the present disclosure. For example, the exemplary method (400) can be used to operate... Figures 1 to 3 , Figure 5 The aircraft 100, or some other aircraft having a boundary layer ingestion system, including a distributed fan array as described herein. It should be understood that the methods (400) discussed herein are for illustrative purposes and not for limitation.

[0088] At (402), method (400) includes receiving data by one or more processors of the aircraft's computing system indicative of one or more operating conditions associated with the aircraft. The aircraft may include a fuselage extending between a front and rear end, and a fan array including fans mounted to and circumferentially arranged around the rear end of the fuselage. As will be explained below, the one or more processors may use the data to determine boundary layer ingestion requirements for each fan in the fan array.

[0089] Operating conditions may include, but are not limited to, environmental conditions (e.g., ambient air temperature, humidity, wind conditions, air pressure, weather conditions, etc.), the airspeed of the aircraft, the altitude of the aircraft, the health status of one or more fans in the fan array, the health status of one or more primary thrusters or their components, the electrical load of the aircraft and / or the current power required by the system, the sensed or derived velocity of the boundary layer airflow at each fan in the fan array, or a combination of the foregoing. Operating conditions may be sensed, calculated, or provided values.

[0090] At (404), method (400) includes determining a boundary layer intake requirement for each fan by one or more processors, at least in part, based on data. The boundary layer intake requirement determined for a given fan of the fan array can be a value corresponding to thrust output required by the fan to optimally reduce drag on the aircraft along the fuselage at a local location associated with the given fan. For example, the boundary layer intake requirement for a fan, i.e., the optimal thrust output to reduce drag on the aircraft at that local location, can be determined based on environmental conditions and the velocity of the boundary layer airflow at the given fan. As an example, one or more processors can look up the boundary layer intake requirement using environmental conditions and the velocity of the boundary layer airflow at the given fan, for example, by looking up a table. In this regard, the boundary layer intake requirement for a given fan can be determined at least in part based on the local velocity and environmental conditions at the given fan, as well as other possible operating conditions. A boundary layer intake requirement can be determined for each fan of the fan array.

[0091] At (406), method (400) includes controlling the thrust output of the fans to their respective thrust outputs, at least in part, based on their respective boundary layer intake requirements. For example, in controlling the thrust output of the fans to their respective thrust outputs, one or more processors may independently control the fans to their respective rotational speeds, at least in part, based on their respective boundary layer intake requirements. In this respect, the fans can locally reduce drag on the aircraft in an optimal manner. Additionally or alternatively, one or more processors may independently control the pitch position of the fan blades of each fan, at least in part, based on their respective boundary layer intake requirements. Additionally or alternatively, one or more processors may independently control the pitch position of the inlet guide vanes of each fan, at least in part, based on their respective boundary layer intake requirements.

[0092] Figure 8 An example computing system 500 according to an exemplary embodiment of the present disclosure is provided. For example, the computing system 190 described herein may include various components and perform various functions of the computing system 500 described below.

[0093] like Figure 8As shown, computing system 500 may include one or more computing devices 510. Computing device 510 may include one or more processors 510A and one or more memory devices 510B. The one or more processors 510A may include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and / or other suitable processing device. The one or more memory devices 510B may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard disk drives, flash drives, and / or other memory devices.

[0094] One or more memory devices 510B may store information accessible by one or more processors 510A, including computer-readable instructions 510C executable by one or more processors 510A. Instructions 510C may be any set of instructions that, when executed by one or more processors 510A, cause one or more processors 510A to perform operations. In some embodiments, instructions 510C may be executed by one or more processors 510A to cause one or more processors 510A to perform operations, such as any operations and functions configured, for example, to control the operation of a boundary layer intake fan, such as computing system 500 and / or computing device 510. Instructions 510C may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, instructions 510C may be executed in logically and / or virtually decoupled threads on processor 510A. Memory device 510B may also store data 510D accessible by processor 510A. For example, data 510D may include models, lookup tables, databases, etc.

[0095] The computing device 510 may also include a network interface 510E for communicating, for example, with other components of the system 500 (e.g., via a communication network). The network interface 510E may include any suitable components for engaging with one or more networks, including, for example, a transmitter, receiver, port, controller, antenna, and / or other suitable components. One or more devices may be configured to receive one or more instructions from or to one or more computing devices 510.

[0096] The techniques discussed herein refer to computer-based systems and the actions taken by computer-based systems, as well as the information sent to and from computer-based systems. Those skilled in the art will recognize that the inherent flexibility of computer-based systems allows for a wide variety of possible configurations, combinations, and divisions of tasks and functions among components. For example, the processes discussed herein can be implemented using a single computing device or a combination of multiple computing devices. Databases, memory, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0097] Although specific features of various embodiments may be shown in some figures but not others, this is merely for convenience. Any feature of the figures may be referenced and / or claimed in conjunction with any feature of any other figure, based on the principles of this disclosure.

[0098] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims, but may include other examples that would occur to a person skilled in the art. These other examples are intended to be within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0099] Further aspects of the invention are provided by way of the subject matter of the following clauses:

[0100] 1. An aircraft comprising: a fuselage extending between a front end and a rear end; and a fan array including fans mounted to the rear end of the fuselage and circumferentially arranged around the rear end of the fuselage, the fans being positioned to draw in boundary layer airflow flowing along the fuselage, at least two of the fans having different sizes.

[0101] 2. According to any of the aircraft described in the preceding paragraph, wherein the at least two fans comprise a first fan, a second fan, and a third fan, each of different sizes.

[0102] 3. According to any of the aircraft described in the preceding paragraph, each fan in the fan array is an electrically driven fan.

[0103] 4. According to any of the aircraft described in the preceding paragraph, each fan in the fan array has an associated motor operatively connected thereto.

[0104] 5. According to any of the aircraft described in the preceding paragraph, wherein the fuselage of the aircraft defines a centerline, and wherein the fans of the fan array include at least two fans primarily positioned above the centerline and at least two fans primarily positioned below the centerline.

[0105] 6. The aircraft according to any of the preceding paragraph, wherein the aircraft defines a lateral direction and a longitudinal centerline, and wherein the at least two fans primarily positioned above the centerline comprise a first fan and a second fan, wherein the first fan is positioned along the lateral direction on a first side of the aircraft, and the second fan is positioned along the lateral direction on a second side of the aircraft, the first side and the second side being defined by the longitudinal centerline.

[0106] 7. According to any of the aircraft described in the preceding paragraph, wherein the at least two fans mainly positioned below the centerline include a third fan, a fourth fan, and a fifth fan positioned between the third fan and the fourth fan, and wherein the axis of rotation of the fifth fan is aligned in the lateral direction with the longitudinal centerline defined by the aircraft.

[0107] 8. According to any of the aircraft described in the preceding paragraph, wherein the at least two fans primarily positioned above the centerline comprise a first group of fans and a second group of fans, the fans of the first group being positioned laterally on a first side of the aircraft, and the fans of the second group being positioned laterally on a second side of the aircraft, the first side and the second side being defined by the longitudinal centerline of the aircraft, and wherein the first group of fans comprises at least three fans and the second group of fans comprises at least three fans.

[0108] 9. According to any of the aircraft described in the preceding paragraph, at least one fan of the fan array includes an inlet guide vane positioned upstream of a plurality of fan blades of the at least one fan.

[0109] 10. According to any of the aircraft described in the preceding paragraph, at least a portion of at least one of the fans extends behind the leading edge of the vertical stabilizer of the aircraft.

[0110] 11. According to any of the aircraft described in the preceding paragraph, wherein the fuselage has a non-circular cross-sectional shape.

[0111] 12. The aircraft according to any of the preceding paragraph, wherein the aircraft defines a circumferential direction, and wherein the aircraft further comprises: an outer nacelle surrounding each fan of the fan array; and at least one partition wall connecting the fuselage to the outer nacelle and separating adjacent fans of the fan array.

[0112] 13. According to any of the aircraft described in the preceding paragraph, wherein the fan is capable of independent control.

[0113] 14. An aircraft comprising: a fuselage extending between a front end and a rear end; a distributed fan array having a plurality of fans mounted to and arranged around the rear end of the fuselage, the plurality of fans being positioned to extract boundary layer airflow; and a computing system having one or more processors configured to independently control the thrust output of at least two fans of the fan array.

[0114] 15. According to any of the aircraft described in the preceding paragraph, wherein when independently controlling the thrust output of at least two fans of the fan array, the one or more processors are configured to independently control the thrust output of each fan in the fan array.

[0115] 16. According to any of the aircraft described in the preceding paragraph, wherein when the thrust output of the at least two fans of the fan array is controlled independently of each other, the one or more processors are configured to: receive data indicating one or more operating conditions associated with the aircraft; determine a boundary layer intake requirement for each of the at least two fans based at least in part on the data, and wherein the at least two fans of the fan array are independently controlled to the thrust output of the at least two fans based at least in part on the respective boundary layer intake requirements of the at least two fans.

[0116] 17. According to any of the aircraft described in the preceding paragraph, wherein the data indicating the one or more operating conditions associated with the aircraft includes the velocity of the boundary layer airflow sensed or derived at each of the at least two fans of the fan array.

[0117] 18. According to any of the aircraft described in the preceding paragraph, wherein when the thrust output of the at least two fans of the fan array is controlled independently, the first fan and the second fan of the at least two fans are controlled to their respective rotational speeds.

[0118] 19. According to any of the aircraft described in the preceding paragraph, wherein when the thrust output of the at least two fans of the fan array is controlled independently, the inlet guide vanes of the first fan and the inlet guide vanes of the second fan of the at least two fans are independently controlled to their respective pitch positions.

[0119] 20. A method of operating an aircraft, the method comprising: receiving, via one or more processors of a computing system of the aircraft, data indicating one or more operating conditions associated with the aircraft, the aircraft having a fuselage extending between a front end and a rear end, the aircraft further comprising a fan array including fans mounted to the rear end of the fuselage and circumferentially arranged around the rear end of the fuselage, the fans being positioned to draw in boundary layer airflow flowing along the fuselage; and, by the one or more processors, determining a boundary layer intake requirement for each of the fans, at least in part based on the data, and controlling the fans to their respective thrust outputs, at least in part based on the respective boundary layer intake requirements of the fans.

Claims

1. An aircraft, characterized in that comprising: a fuselage extending between a forward end and an aft end; a fan array including fans mounted to and arranged circumferentially about the aft end of the fuselage, the fans positioned to ingest a boundary layer airflow flowing along the fuselage, at least two of the fans having different sizes; a first sensor positioned at or proximate to a first one of the fans of the fan array and within the boundary layer airflow flowing along the fuselage; a second sensor positioned at or proximate to a second one of the fans of the fan array and within the boundary layer airflow flowing along the fuselage; a computing system having one or more processors configured to: receive, from the first and second sensors, respectively, data indicative of one or more operating conditions associated with the boundary layer airflow of the first and second fans; determine, based at least in part on the data, a first boundary layer ingestion draw requirement of the first fan and a second boundary layer ingestion draw requirement of the second fan, and operate the first and second fans based at least in part on the first and second boundary layer ingestion draw requirements, respectively; and at least one partition wall connecting the fuselage with an outboard nacelle and separating adjacent ones of the fans of the fan array, wherein a leading edge of the at least one partition wall is aligned with or positioned aft of a leading edge of a fan casing of at least one of the fans along a longitudinal direction, wherein the fan casing of the at least one fan is positioned aft of a leading edge of the outboard nacelle along the longitudinal direction.

2. The aircraft of claim 1, wherein, wherein the at least two fans include first, second, and third fans each having different sizes.

3. The aircraft of claim 1, wherein, wherein each of the fans of the fan array is an electrically driven fan.

4. The aircraft of claim 1, wherein, wherein each of the fans of the fan array has an associated electric machine operably coupled thereto.

5. The aircraft of claim 1, wherein, wherein the fuselage of the aircraft defines a centerline, and wherein the fans of the fan array include at least two fans positioned above the centerline and at least two fans positioned below the centerline.

6. The aircraft of claim 5, wherein, wherein the aircraft defines a lateral direction and a longitudinal centerline, and wherein the at least two fans positioned above the centerline include first and second fans, wherein the first fan is positioned on a first side of the aircraft along the lateral direction and the second fan is positioned on a second side of the aircraft along the lateral direction, the first and second sides defined by the longitudinal centerline.

7. The aircraft of claim 5, wherein, wherein the at least two fans positioned below the centerline include third, fourth, and fifth fans positioned between the third and fourth fans, and wherein a rotational axis of the fifth fan is aligned with a longitudinal centerline defined by the aircraft along a lateral direction.

8. The aircraft of claim 7, wherein, wherein the at least two fans positioned above the centerline include a first group of fans and a second group of fans, the fans of the first group positioned along a lateral direction on a first side of the aircraft and the fans of the second group positioned along the lateral direction on a second side of the aircraft, the first side and the second side defined by a longitudinal centerline of the aircraft, and wherein the first group of fans includes at least three fans and the second group of fans includes at least three fans.

9. The aircraft of claim 1, wherein, wherein at least one of the fans of the fan array includes an inlet guide vane positioned upstream of a plurality of fan blades of the at least one fan.

10. The aircraft of claim 1, wherein, wherein at least a portion of at least one of the fans extends aft of a leading edge of a vertical stabilizer of the aircraft.

11. The aircraft of claim 1, wherein, wherein the fuselage has a non-circular cross-sectional shape.

12. The aircraft of claim 1, wherein, wherein the aircraft defines a circumferential direction, and wherein the aircraft further includes: an outer nacelle surrounding each of the fans of the fan array.

13. The aircraft of claim 1, wherein, wherein the fans are independently controllable.

14. An aircraft characterized by, including: a fuselage extending between a forward end and an aft end; a distributed fan array having a plurality of fans mounted to and arranged about the aft end of the fuselage, the plurality of fans positioned to ingest a boundary layer airflow; a first sensor placed at or proximate to a first fan of the plurality of fans and within the boundary layer airflow flowing along the fuselage; a second sensor placed at or proximate to a second fan of the plurality of fans and within the boundary layer airflow flowing along the fuselage; a computing system having one or more processors configured to independently control thrust output of at least two fans of the fan array, the computing system further configured to: receive, from the first sensor and the second sensor, respectively, data indicative of one or more operating conditions associated with the boundary layer airflow of the first fan and the second fan; determine, based at least in part on the data, a first boundary layer ingestion intake requirement of the first fan and a second boundary layer ingestion intake requirement of the second fan, and operate the first fan and the second fan based at least in part on the first boundary layer ingestion intake requirement and the second boundary layer ingestion intake requirement, respectively; and at least one partition wall connecting the fuselage with an outer nacelle and separating adjacent ones of the fans of the fan array, wherein a leading edge of the at least one partition wall is aligned with or positioned aft of a leading edge of a fan casing of at least one of the fans along a longitudinal direction, wherein the fan casing of the at least one fan is positioned along the longitudinal direction aft of a leading edge of the outer nacelle.

15. The aircraft of claim 14, wherein, wherein in independently controlling the thrust output of the at least two fans of the fan array, the one or more processors are configured to independently control the thrust output of each fan of the fan array.

16. The aircraft of claim 14, wherein, wherein the data indicative of the one or more operating conditions associated with the aircraft includes a velocity of the boundary layer airflow sensed or derived at each of the at least two fans of the fan array.

17. The aircraft of claim 14, wherein, wherein, in independently controlling the thrust output of the at least two fans of the fan array, a first fan of the at least two fans and a second fan of the at least two fans are controlled to respective rotational speeds.

18. The aircraft of claim 14, wherein, wherein, in independently controlling the thrust output of the at least two fans of the fan array, an inlet guide vane of a first fan of the at least two fans and an inlet guide vane of a second fan of the at least two fans are independently controlled to respective pitch positions.

19. A method of operating an aircraft, characterized by, The method comprises: receiving, by one or more processors of a computing system of an aircraft, data indicative of one or more operating conditions associated with the aircraft, the aircraft having a fuselage extending between a forward end and an aft end, the aircraft further including a fan array comprising fans mounted to and arranged circumferentially about the aft end of the fuselage, the fans positioned to ingest a boundary layer airflow flowing along the fuselage, wherein the data is received from a first sensor and a second sensor, the first sensor positioned at or proximate to a first fan of the fans of the fan array and within the boundary layer airflow flowing along the fuselage, the second sensor positioned at or proximate to a second fan of the fans of the fan array and within the boundary layer airflow flowing along the fuselage; determining, by the one or more processors, a first boundary layer ingestion requirement for the first fan and a second boundary layer ingestion requirement for the second fan based at least in part on the data, and controlling the first fan and the second fan based at least in part on the first boundary layer ingestion requirement and the second boundary layer ingestion requirement, respectively, wherein a leading edge of the at least one partition wall is aligned or positioned aft of a leading edge of a fan casing of at least one of the fans along a longitudinal direction, wherein the fan casing of the at least one fan is positioned aft of a leading edge of an outer nacelle along the longitudinal direction.

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