Patent Publication Number: US-11384649-B1

Title: Heat exchanger and flow modulation system

Description:
FIELD 
     The present subject matter relates generally to heat exchanger systems and systems for flow modulation therefor. The present subject matter relates particularly to heat exchanger and flow modulation systems for gas turbine engines and propulsion systems. 
     BACKGROUND 
     Propulsion systems and gas turbine engines are challenged with thermal management of increasingly higher thermal loads. The increasingly higher thermal loads are due in part to increasingly higher energy requirements from vehicles attached to the propulsion systems and gas turbine engines. The higher energy requirements are due in part to increasing electrification of vehicles such as aircraft or increased ability of propulsion systems and gas turbine engines to generate electricity or require greater electric loads. 
     Higher thermal loads may also result from improved engine designs and materials that allow for systems to generate and withstand higher temperatures. Higher operating temperatures may require lubricants and fuels to receive larger magnitudes of heat and thermal energy. 
     It is significant that improved engine designs are not adversely offset by inefficient heat exchange systems. Conventional heat exchange systems may operate primarily as a function of engine speed. However, such heat exchange systems may be insufficient at low speed or part-power conditions. Also, such heat exchange systems may decrease engine efficiency at high power conditions or other conditions that may require less heat transfer performance. 
     Conventional heat exchange systems may utilize doors, flaps, scoops, or bleed injectors. However, such systems may adversely increase engine weight such as to negate improved engine designs and materials that may reduce engine weight. 
     As such, there is a need for improved heat exchanger systems that can meet the needs resulting from higher thermal loads. Still further, there is a need for improved operation of heat exchange systems at part-power conditions and high power conditions. 
     BRIEF DESCRIPTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     A propulsion system is accordance with an aspect of present disclosure is provided. The propulsion system includes a first vane extended along the radial direction. The first vane is configured to rotate relative to a vane axis extended along the radial direction. A second vane is extended along the radial direction and is positioned aft along the axial direction of the first vane. The second vane forms an inlet opening proximate to a second vane leading edge, and the second vane forms an outlet opening proximate to a second vane trailing edge. The inlet opening and the outlet opening together allow a flow of fluid through the second vane. A heat exchanger is positioned within the second vane. The inlet opening and the outlet opening allow the flow of fluid in fluid communication with the heat exchanger. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  is a perspective view of an exemplary vehicle including a propulsion system having a heat exchanger system in accordance with aspects of the present disclosure; 
         FIG. 2  is a schematic cross-sectional view of an exemplary embodiment of a propulsion system having a heat exchanger system in accordance with aspects of the present disclosure; 
         FIG. 3  is a schematic cross-sectional view of an exemplary embodiment of a propulsion system having a heat exchanger system in accordance with aspects of the present disclosure; 
         FIG. 4  is a perspective view of an exemplary embodiment of the heat exchanger system in a closed position accordance with aspects of the present disclosure; 
         FIG. 5  is a perspective view of the exemplary embodiment of the heat exchanger system of  FIG. 4  in an open position accordance with aspects of the present disclosure; 
         FIG. 6  is a perspective view of an exemplary embodiment of the heat exchanger system in a closed position accordance with aspects of the present disclosure; 
         FIG. 7  is a perspective view of the exemplary embodiment of the heat exchanger system of  FIG. 6  in an open position accordance with aspects of the present disclosure; and 
         FIG. 8  is a circumferential view of an embodiment of a heat exchanger in accordance with aspects of the present disclosure. 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. 
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. 
     Embodiments of a heat exchanger and flow modulation system are provided that may meet needs associated with higher thermal loads and improved operation at part-power conditions and high power conditions. Embodiments of an engine including the heat exchanger and flow modulation system include a first vane positioned at least partially forward of a second vane, in which a heat exchanger is positioned within the second vane. The first vane is articulatable to adjust a flow of fluid through an inlet opening at the second vane into thermal communication with the heat exchanger. The articulatable first vane adjusts an amount of thermal communication of the flow of fluid with the heat exchanger, such as based on operating condition of the engine or thermal loading. The first vane may be attached to a variable guide vane system, rather than doors, flaps, scoops, or bleed injectors, such as to desirably alter the amount of fluid and heat transfer with the heat exchanger. 
     Embodiments provided herein may avoid engine weight increases or complex systems, such as via utilizing variable vane actuator systems such as utilized for compressor sections. The flow of fluid through the second vane allows for adjusting heat exchanger frontal area via tangential flow without significantly modifying bulk flow pattern in the flowpath surrounding the vanes. Heat exchanger pods or pylons inside the vane may allow for diffusing inlet momentum to minimize cold-side pressure drop at the heat exchanger. Positioning of an outlet opening at the second vane allows the cooling fluid to flow through the second vane and discharge into a low static pressure region, such as to minimize undesired aerodynamic effects to flows outside the vanes thereacross. 
     Embodiments of the engine, heat exchanger, and flow modulation system may allow for adaptive cycle operation and performance from a two-stream engine (e.g., fan flow stream and core flow stream) using the variable first vane to direct flow toward the heat exchanger at the second vane during a thermal management mode. The first vane may articulate to allow flow to substantially bypass the heat exchanger during a propulsion mode. 
     Referring now to the drawings, in  FIG. 1 , an exemplary embodiment of a vehicle  100  including a propulsion system  10  and a heat exchanger system  200  according to aspects of the present disclosure is provided. In an embodiment, the vehicle  100  is an aircraft including an aircraft structure or airframe  105 . The airframe  105  includes a fuselage  110  to which wings  120  and an empennage  130  are attached. The propulsion system  10  according to aspects of the present disclosure is attached to one or more portions of the airframe. In various embodiments, the heat exchanger system  200  is a system configured to articulate a vane structure to desirably provide cooling fluid, such as air or oxidizer, to a heat exchanger positioned within a downstream vane. The cooling fluid removes heat or thermal energy from one or more fluids, such as, but not limited to, liquid and/or gaseous fuel, lubricant, hydraulic fluid, pneumatic fluid, heat transfer fluid, or cooling fluid for an electric machine, electronics, computing system, environmental control system, gear assembly, or other system or structure. 
     In certain instances, the propulsion system  10  is attached to an aft portion of the fuselage  110 . In certain other instances, the propulsion system  10  is attached underneath, above, or through the wing  120  and/or portion of the empennage  130 . In various embodiments, the propulsion system  10  is attached to the airframe  105  via a pylon or other mounting structure. In still other embodiments, the propulsion system  10  is housed within the airframe, such as may be exemplified in certain supersonic military or commercial aircraft. 
     Referring now to the drawings,  FIG. 2  is a schematic partially cross-sectioned side view of an exemplary gas turbine engine  10  herein referred to as “engine  10 ” as may incorporate various embodiments of the present invention. The engine  10  may particularly be configured as a gas turbine engine for an aircraft. Although further described herein as a turbofan engine, the engine  10  may define a turboshaft, turboprop, or turbojet gas turbine engine, including marine and industrial engines and auxiliary power units. As shown in  FIG. 1 , the engine  10  has a longitudinal or axial centerline axis  12  that extends therethrough for reference purposes. An axial direction A is extended co-directional to the axial centerline axis  12  for reference. The engine  10  further defines an upstream end  99  and a downstream end  98  for reference. In general, the engine  10  may include a fan assembly  14  and a core engine  16  disposed downstream from the fan assembly  14 . 
     The core engine  16  may generally include a substantially tubular outer casing  18  that defines an annular inlet  20 . The outer casing  18  encases or at least partially forms, in serial flow relationship, a compressor section having a booster or low pressure (LP) compressor  22 , a high pressure (HP) compressor  24 , a heat addition system  26 , an expansion section or turbine section including a high pressure (HP) turbine  28 , a low pressure (LP) turbine  30  and a jet exhaust nozzle section  32 . A high pressure (HP) rotor shaft  34  drivingly connects the HP turbine  28  to the HP compressor  24 . A low pressure (LP) rotor shaft  36  drivingly connects the LP turbine  30  to the LP compressor  22 . The LP rotor shaft  36  may also be connected to a fan shaft  38  of the fan assembly  14 . In particular embodiments, as shown in  FIG. 1 , the LP rotor shaft  36  may be connected to the fan shaft  38  via a reduction gear  40  such as in an indirect-drive or geared-drive configuration. 
     As shown in  FIG. 2 , the fan assembly  14  includes a plurality of fan blades  42  that are coupled to and that extend radially outwardly from the fan shaft  38 . An annular fan casing or nacelle  44  circumferentially may surround the fan assembly  14  and/or at least a portion of the core engine  16 . It should be appreciated by those of ordinary skill in the art that the nacelle  44  may be configured to be supported relative to the core engine  16  by a plurality of circumferentially-spaced outlet guide vanes or struts  46 . Moreover, at least a portion of the nacelle  44  may extend over an outer portion of the core engine  16  so as to define a fan flow passage  48  therebetween. However, it should be appreciated that various configurations of the engine  10  may omit the nacelle  44 , or omit the nacelle  44  from extending around the fan blades  42 , such as to provide an open rotor or propfan configuration of the engine  10  depicted in  FIG. 3 . 
     It should be appreciated that combinations of the shaft  34 ,  36 , the compressors  22 ,  24 , and the turbines  28 ,  30  define a rotor assembly  90  of the engine  10 . For example, the HP shaft  34 , HP compressor  24 , and HP turbine  28  may define a high speed or HP rotor assembly of the engine  10 . Similarly, combinations of the LP shaft  36 , LP compressor  22 , and LP turbine  30  may define a low speed or LP rotor assembly of the engine  10 . Various embodiments of the engine  10  may further include the fan shaft  38  and fan blades  42  as the LP rotor assembly. In other embodiments, the engine  10  may further define a fan rotor assembly at least partially mechanically de-coupled from the LP spool via the fan shaft  38  and the reduction gear  40 . Still further embodiments may further define one or more intermediate rotor assemblies defined by an intermediate pressure compressor, an intermediate pressure shaft, and an intermediate pressure turbine disposed between the LP rotor assembly and the HP rotor assembly (relative to serial aerodynamic flow arrangement). 
     During operation of the engine  10 , a flow of air, shown schematically by arrows  74 , enters an inlet  76  of the engine  10  defined by the fan case or nacelle  44 . A portion of air, shown schematically by arrows  80 , enters the core engine  16  through a core inlet  20  defined at least partially via the outer casing  18 . The flow of air is provided in serial flow through the compressors, the heat addition system, and the expansion section via a core flowpath  70 . The flow of air  80  is increasingly compressed as it flows across successive stages of the compressors  22 ,  24 , such as shown schematically by arrows  82 . The compressed air  82  enters the heat addition system  26  and mixes with a liquid and/or gaseous fuel and is ignited to produce combustion gases  86 . It should be appreciated that the heat addition system  26  may form any appropriate system for generating combustion gases, including, but not limited to, deflagrative or detonative combustion systems, or combinations thereof. The heat addition system  26  may include annular, can, can-annular, trapped vortex, involute or scroll, rich burn, lean burn, rotating detonation, or pulse detonation configurations, or combinations thereof. 
     The combustion gases  86  release energy to drive rotation of the HP rotor assembly and the LP rotor assembly before exhausting from the jet exhaust nozzle section  32 . The release of energy from the combustion gases  86  further drives rotation of the fan assembly  14 , including the fan blades  42 . A portion of the air  74  bypasses the core engine  16  and flows across the fan flow passage  48 , such as shown schematically by arrows  78 . 
     Referring now to  FIG. 3 , another exemplary embodiment of the engine  10  is provided. The embodiment provided in  FIG. 3  is configured substantially similarly as described in regard to  FIG. 2 . In  FIG. 3 , the engine  10  is configured as a three-stream engine including the fan flow passage  48 , the core flowpath  70 , and a core bypass or third stream  71 . The core flowpath  70  is extended through at least the high pressure compressor  24 , the heat addition system  26 , and the high pressure turbine  32 . The core bypass or third stream flowpath  71  is extended from downstream of the low or intermediate pressure compressor  22  and bypasses the core flowpath  70  at the HP compressor  24  and heat addition system  26 . In certain embodiments, the third stream flowpath  71  is extended into fluid communication downstream of the vanes  46  at the fan flow passage  48 . 
     It should be appreciated that  FIG. 2  depicts and describes a two-stream engine having the fan flow passage  48  and the core flowpath  70 . The embodiment depicted in  FIG. 2  has a nacelle  44  surrounding the fan blades  42 , such as to provide noise attenuation, blade-out protection, and other benefits known for nacelles.  FIG. 3  depicts and describes a three-stream engine having the fan flow passage  48 , the core flowpath  70 , and the third stream flowpath  71 . The embodiment depicted in  FIG. 3  is configured with the fan blades  42  being unducted by a nacelle, such as to form an open rotor engine. In various embodiments, the unducted open rotor engine may form a two-stream engine such as described with regard to  FIG. 2 . Alternatively, the ducted engine including the nacelle  44  may form a three-stream engine such as described in regard to  FIG. 3 . Still further embodiments may position the heat exchanger and flow modulation system further described herein in an engine forming a ramjet, a supersonic combustion ramjet (scramjet), a turboprop gas turbine engine, a turboshaft gas turbine engine, or a turbojet engine. 
     Referring now to  FIGS. 4-7 , perspective views of embodiments of a heat exchanger system  200  are provided. Embodiments of the system  200  include a first vane  210  extended along the radial direction R. The first vane  210  is operably connected to an actuation system  250  configured to rotate the first vane  210  relative to a vane axis  216  extended along the radial direction R. A second vane  220  is extended along the radial direction R. The second vane  220  is positioned aft along the axial direction A of the first vane  210 . 
     The vanes generally form airfoils each having a leading edge, a trailing edge, a pressure side, and a suction side. The second vane  220  forms an inlet opening  226  proximate to a second vane leading edge  222 . The second vane  220  forms an outlet opening  228  proximate to a second vane trailing edge  224 . The inlet opening  226  and the outlet opening  228  together allow a flow of fluid, such as air or oxidizer generally described in regard to the engine  10  in  FIGS. 2-3 , through the second vane  220 . 
     A heat exchanger  230  is positioned within the second vane  220 . The inlet opening  226  and the outlet opening  228  allow for the flow of fluid to enter into fluid communication with the heat exchanger  230 . In various embodiments, the heat exchanger  230  includes a supply conduit  234  and a return conduit  232 . Each conduit includes walls allowing for a flow of a thermal load into the heat exchanger  230 . The heat exchanger  230  fluidly separates the flow of the thermal load from the flow of fluid allowed to flow through second vane  220 . The supply conduit  234  is configured to provide the flow of the thermal load into the heat exchanger  230 . The return conduit  232  is configured to remove the flow of the thermal load from the heat exchanger  230 . In a particular embodiment, the supply conduit  234  is positioned proximate to an aft or trailing edge  224  of the second vane  220  and the return conduit  232  is positioned proximate to a forward or leading edge  222  of the second vane  220 . As such, the thermal load flowing through the heat exchanger  230  is provided in counter-flow relative to the flow of fluid through the second vane  220 , such as to improve heat transfer. 
     Referring back to  FIGS. 2-3 , and in conjunction with  FIGS. 4-7 , in certain embodiments, the engine  10  includes an outer radial wall  205  extended along the axial direction A and an inner radial wall  206  extended substantially co-directional to the outer radial wall  205 . The outer radial wall  205  and the inner radial wall  206  together form a flowpath extended substantially along the axial direction A. In various embodiments, the flowpath is the fan flow passage  48 , the core flowpath  70 , or the third stream flowpath  71 . The first vane  210  and the second vane  220  are each extended along the radial direction R through the flowpath. 
     In one embodiment, the outer radial wall  205  and the inner radial wall  206  form an inlet section configured to receive the flow of fluid into the flowpath, such as depicted and described at the inlet  20  at the compressor section. In such an embodiment, the first vane  210  and the second vane  220  are extended through the core flowpath  70 . In a particular embodiment, the first vane  210  and the second vane  220  are extended through the core flowpath at the compressor section, such as at the intermediate or low pressure compressor  22 . In still another embodiment, the first vane  210  and the second vane  220  may be extended at the core flowpath  70  between the LP compressor  22  and the HP compressor  24 . 
     In another embodiment, the outer radial wall  205  is formed at the nacelle  44 , such as depicted in  FIG. 2 . The first vane  210  and the second vane  220  are positioned aft along the axial direction A of the plurality of fan blades  42 . The inner radial wall  206  is formed at the outer casing  16  of the core engine  18 . The flowpath includes at least a portion of the fan flow passage  48 . The first vane  210  and the second vane  220  are extended through the fan flow passage  48 . 
     In still another embodiment, such as depicted in  FIG. 3 , the first vane  210  and the second vane  220  are extended through the flowpath formed by the third stream passage  71 . 
     In yet another embodiment, the first vane  210  and the second vane  220  are extended from the outer casing  16  of the core engine  18  into the fan flow passage  48 . In a particular embodiment, such as depicted in  FIG. 3 , the first vane  210  and the second vane  220  are extended from the outer casing  16  into the fan flow passage  48  of an unducted rotor engine. 
     Various embodiments of the system  200  may include a plurality of the first vane  210  positioned in circumferential arrangement. The system  200  may further include a plurality of the second vane  220  positioned in circumferential arrangement. In particular embodiments, the inlet opening  226  is positioned through the pressure side  227  of the second vane  220 . In a still particular embodiment, the outlet opening  228  is positioned through a suction side  229  of the second vane  220 . 
     Referring briefly to  FIG. 8 , a circumferential view from upstream looking downstream of an exemplary embodiment of the system  200  of  FIGS. 4-7  is provided. Figs. Certain embodiments of the system  200  position the first vane  210  offset along the circumferential direction C from the second vane  220 . As such, the first vane  210  and the second vane  220  are positioned at circumferential locations different from one another. 
     Referring back to  FIGS. 4-7 , the first vane  210  includes a first vane trailing edge  214  and a first vane leading edge  212 . In certain embodiments, the first vane trailing edge  214  is co-axial to at least at portion of the second vane leading edge  222 . In a particular embodiment, the first vane trailing edge  214  is co-axial to the inlet opening  226  at the second vane  210 . 
     During operation of the engine  10  such as described above, the first vane  210  is configured to actively adjust, modulate, alter, or otherwise direct the flow of fluid into the inlet opening  226  of the second vane  210  (such as depicted in  FIG. 5  and  FIG. 7 ) or away from the inlet opening  226  (such as depicted in  FIG. 4  and  FIG. 6 ) via rotation of the first vane  210  along the vane axis  216 . The flow of fluid, such as air or oxidizer generally, is provided through the flowpath  75  such as described above with regard to the fan flow passage  48 , the core flowpath  70 , or the third stream flowpath  71 . When the first vane  210  is modulated to an open position, such as depicted in  FIG. 4  and  FIG. 6 , the flow of fluid, depicted schematically via arrows  77   a , passes across the first vane  210  and the second vane  220  without substantially entering the second vane  220  through the inlet opening  226 . when the first vane  210  is modulated to a closed position, such as depicted in  FIG. 5  and  FIG. 7 , a portion of the flow of fluid, depicted schematically via arrows  77   b , is directed into the second vane  220  into thermal communication with the heat exchanger  230 . 
     In various embodiments, the flow of the thermal load flowing through the heat exchanger  230  is one or more of a flow of lubricant, a flow of fuel, a flow of hydraulic fluid, or a flow of heat transfer fluid, or combinations thereof. During operation of the engine  10 , the first vane  210  is actuated along its vane axis  216  to adjust a mass flow or volumetric flow of cooling fluid, such as the air or oxidizer generally depicted via arrows  77   b , directed into thermal communication with the heat exchanger  230  within the second vane  220 . Increased transfer of heat or thermal energy from the thermal load at the heat exchanger  230  is generated by closing the first vane  210  to direct greater amounts of cooling fluid  77   b  into the second vane  220 . The flow of cooling fluid is allowed to egress from the second vane  220  through the outlet opening  228 , such as depicted in  FIG. 5  and  FIG. 7  via arrows  77   c.    
     Modulation of the first vane  210  allows for altering aerodynamics at a duct forming the flowpath  75 , such as to allow the heat exchanger  230  to capture total pressure and discharge the flow of fluid  77   c  into a relatively low static pressure region at the suction side  228  of the second vane  220 . The second vane  220  may include features to sink the flow of fluid  77   b  into static pressure. Such features may include the particular positions of the inlet opening  226 , the outlet opening  228 , the first vane  210  relative to the adjacent second vane  220 , or a surface roughness, bumps, ridges, protrusions, perturbations, or dimples at or inside the second vane  220 . 
     Methods for operation include one or more steps such as described above. Additional steps may include modulating the first vane  210  into an increased thermal attenuation mode via closing the first vane  210  and directing the flow of fluid into inlet opening  226  at the second vane  220 . Steps may further include modulating the first vane  210  into a propulsion mode via opening the first vane  210  and directing the flow of fluid away from the inlet opening  226 . As such, the thermal attenuation mode directs increased flow into thermal communication with the heat exchanger  230  and the propulsion mode directs less flow into the thermal communication with the heat exchanger  230 . Certain embodiments may correspond the propulsion mode to a high-power output (e.g., takeoff or climb-out power in a landing-takeoff cycle) of the engine  10 . Still certain embodiments may correspond the thermal attenuation mode to a low-power or part-power output (e.g., idle or cruise condition in a landing-takeoff cycle). 
     Embodiments of the heat exchanger  200  provided herein may improve overall engine efficiency and thermal management performance without adversely impacting engine weight or aerodynamics. Embodiments provided herein allow for adjusting an effective frontal area of the heat exchanger  230 , such as may indicate heat transfer at the heat exchanger  230 , via allowing a tangential flow through the second vane  220  without significantly altering bulk flow pattern of the flow of fluid directed downstream. 
     Referring back to  FIGS. 2-3 , the system may further include a computing system  210  configured to obtain, measure, or otherwise send and receive signals to modulate, open, close, adjust, rotate, or otherwise selectively actuate the first vane  210  to permit or disable the flow of air, or oxidizer generally, through the second vane  220  such as described herein. 
     The computing system  210  can correspond to any suitable processor-based device, including one or more computing devices, such as described above. In certain embodiments, the computing system  210  is a full-authority digital engine controller (FADEC) for a gas turbine engine, or other computing module or controller configured to execute instructions for operating a gas turbine engine. For instance,  FIG. 2  and  FIG. 3  illustrate one embodiment of suitable components that can be included within the computing system  210 . The computing system  210  can include a processor  212  and associated memory  214  configured to perform a variety of computer-implemented functions. 
     As shown, the computing system  210  can include control logic  216  stored in memory  214 . The control logic  216  may include instructions that when executed by the one or more processors  212  cause the one or more processors  212  to perform operations. Additionally, the computing system  210  can also include a communications interface module  230 . In several embodiments, the communications interface module  230  can include associated electronic circuitry that is used to send and receive data. As such, the communications interface module  230  of the computing system  210  can be used to send and/or receive data to/from engine  10  and the heat exchanger system  200 . In addition, the communications interface module  230  can also be used to communicate with any other suitable components of the heat exchanger system  200 , such as the first vane  210  or the actuation system  250 . 
     It should be appreciated that the communications interface module  230  can be any combination of suitable wired and/or wireless communications interfaces and, thus, can be communicatively coupled to one or more components of the compressor section or the engine via a wired and/or wireless connection. 
     Embodiments of the actuation system  250  for the first vane  210  may include a variable guide vane (VGV) system including synchronization rings, clevises, actuators, and linkages as may generally be utilized for compressor sections. Still other embodiments of the actuation system  250  for the first vane  210  may include a pitch adjustment mechanism including motors, rings, clevises, actuators, or linkages as may generally be utilized for fan or propeller blades or vanes. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 
     Further aspects of the invention are provided by the subject matter of the following clauses: 
     1. A propulsion system defining an axial centerline axis, an axial direction co-directional to the centerline axis, a radial direction extended from the centerline axis, and a circumferential direction extended relative to the centerline axis, the system including a first vane extended along the radial direction, and wherein the first vane is configured to rotate relative to a vane axis extended along the radial direction; a second vane extended along the radial direction, and wherein the second vane is positioned aft along the axial direction of the first vane, wherein the second vane forms an inlet opening proximate to a second vane leading edge, and wherein the second vane forms an outlet opening proximate to a second vane trailing edge, wherein the inlet opening and the outlet opening together allow a flow of fluid through the second vane; and a heat exchanger positioned within the second vane, wherein the inlet opening and the outlet opening allow the flow of fluid in fluid communication with the heat exchanger. 
     2. The system of any one or more clauses herein, wherein the first vane is configured to direct the flow of fluid into the inlet opening of the second vane via rotation of the first vane along the vane axis to a closed position. 
     3. The system of any one or more clauses herein, wherein the first vane is configured to direct the flow of fluid away from the inlet opening of the second vane via rotation of the first vane along the vane axis to an open position. 
     4. The system of any one or more clauses herein, the system including a plurality of the first vane positioned in circumferential arrangement. 
     5. The system of any one or more clauses herein, the system including a plurality of the second vane positioned in circumferential arrangement. 
     6. The system of any one or more clauses herein, wherein the inlet opening is positioned through a pressure side of the second vane. 
     7. The system of any one or more clauses herein, wherein the outlet opening is positioned through a suction side of the second vane. 
     8. The system of any one or more clauses herein, wherein the first vane is offset along the circumferential direction from the second vane. 
     9. The system of any one or more clauses herein, wherein a first vane trailing edge is co-axial to at least the second vane leading edge. 
     10. The system of any one or more clauses herein, wherein the first vane trailing edge is co-axial to the inlet opening at the second vane. 
     11. The system of any one or more clauses herein, the system including an outer radial wall extended along the axial direction; and an inner radial wall extended co-directional to the outer radial wall, wherein the outer radial wall and the inner radial wall together form a flowpath extended substantially along the axial direction, and wherein the first vane and the second vane are each extended along the radial direction through the flowpath. 
     12. The system of any one or more clauses herein, wherein the outer radial wall and the inner radial wall form an inlet section configured to receive the flow of fluid into the flowpath. 
     13. The system of any one or more clauses herein, the system including a fan section comprising a plurality of fan blades, wherein a nacelle surrounds the plurality of fan blades, and wherein the outer radial wall is formed at the nacelle, and wherein the first vane and the second vane are positioned aft along the axial direction of the plurality of fan blades; and a core engine, wherein an outer casing surrounds the core engine, and wherein the inner radial wall is formed at the outer casing. 
     14. The system of any one or more clauses herein, the system including a compressor section including a plurality of compressor blades extended along the radial direction through the flowpath, wherein the plurality of compressor blades is surrounded by the outer radial wall, and wherein the first vane and the second vane are positioned at the compressor section. 
     15. The system of any one or more clauses herein, the system including a fan section including a plurality of fan blades, wherein the plurality of fan blades is extended along the radial direction through a fan flow passage; and a compressor section including a plurality of compressor blades extended along the radial direction through the flowpath, wherein the flowpath separates into a core flowpath in fluid communication with a heat addition system, and wherein the flowpath separates into a third stream flowpath in fluid communication with the fan flow passage downstream of the plurality of fan blades. 
     16. The system of any one or more clauses herein, the system including a fan section including a plurality of fan blades, wherein the plurality of fan blades is extended along the radial direction through a fan flow passage; and a core engine, wherein an outer casing surrounds the core engine, wherein the first vane and the second vane are extended from the outer casing aft of the plurality of fan blades. 
     17. The system of any one or more clauses herein, wherein the fan section is unducted, and wherein the plurality of fan blades forms an open rotor configuration. 
     18. The system of any one or more clauses herein, the system including a supply conduit configured to allow a flow of a thermal load into the heat exchanger; and a return conduit configured to remove the flow of the thermal load from the heat exchanger, wherein the flow of fluid in fluid communication with the heat exchanger is a flow of oxidizer, and wherein the heat exchanger allows the flow of oxidizer into thermal communication with the flow of the thermal load. 
     19. The system of any one or more clauses herein, wherein the flow of the thermal load is one or more of a flow of lubricant, a flow of fuel, a flow of hydraulic fluid, or a flow of heat transfer fluid. 
     20. The system of any one or more clauses herein, the system including an actuation system configured to rotate the first vane along the vane axis.