Patent Publication Number: US-2019170453-A1

Title: Heat exchanger low pressure loss manifold

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This disclosure claims priority to U.S. Provisional Patent Application No. 62/593,413 filed Dec. 1, 2017. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with government support under contract number FA8626-16-C-2139 awarded by the United States Air Force. The government has certain rights in the invention. 
    
    
     BACKGROUND 
     A heat exchanger includes inlet structures that distribute flow from a circular conduit into one or many smaller flow passages. High initial total pressure with the inlet manifold is desired to be maintained, with minimal loss, through the heat exchanger and out the exit manifold. Flow Velocity within the relative large spaces provided by the manifold are relatively low compared to airflow velocities desired within the smaller flow passages where thermal transfer occurs. Higher airflow velocities through the flow passages increase thermal transfer efficiencies. Pressure losses between the conduit, manifold and the smaller flow passages can be substantial and reduce airflow velocity and thereby thermal transfer efficiencies. Moreover, upon exiting the flow passages, the airflow expands into the larger space that generates further pressure losses. The combined pressure losses at the inlet and the outlet reduce thermal efficiencies and require structurally larger heat exchangers to accommodate increased demands. 
     Turbine engine manufactures utilize heat exchangers throughout the engine to cool and condition airflow for cooling and other operational needs. Turbine engine improvements have enabled increases in operational temperatures and pressures. The increases in temperatures and pressures improve engine efficiency but also increase demands on all engine components including heat exchangers. 
     Turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal, transfer and propulsive efficiencies. 
     SUMMARY 
     In a featured embodiment, a heat exchanger includes a plurality of flow passages in thermal contact with a cooling flow. The plurality of flow passages include a first end and a second end. An inlet manifold is at the first end of the plurality of flow passages. The inlet manifold includes a plurality of independent splitter passages that communicate airflow to the first end of the plurality of flow passages. An exhaust manifold is at the second end of the plurality of flow passages. 
     In another embodiment according to the previous embodiment, each of the plurality of splitter passages include a flow area between an inlet of the inlet manifold and an outlet of the inlet manifold into the first end of the plurality of passages that are the same. 
     In another embodiment according to any of the previous embodiments, a ratio between an area of the inlet and an area of the outlet of each of the plurality of splitter passages is between 1.5 and 5. 
     In another embodiment according to any of the previous embodiments, the inlet includes a circular shape in cross-section and is divided into passage inlets of equal area that correspond with each of the plurality of splitter passages. 
     In another embodiment according to any of the previous embodiments, each of the passage inlets are pie-shaped in cross-section. 
     In another embodiment according to any of the previous embodiments, each of the passage inlets are circular shaped in cross-section. 
     In another embodiment according to any of the previous embodiments, the outlet includes a rectangular shape in cross-section and is divided into passage outlets of equal area that correspond with the plurality of splitter passages. 
     In another embodiment according to any of the previous embodiments, each of the passage outlets is in communication with more than one of the plurality of flow passages. 
     In another embodiment according to any of the previous embodiments, each of the plurality of splitter passages includes a smooth curved passage without interruption between the inlet and the outlet. 
     In another embodiment according to any of the previous embodiments, the exhaust manifold includes an inlet portion at the second end of the plurality of flow passages and an outlet portion. The exhaust manifold includes a plurality of exhaust passages defining separate flow passages between the inlet portion and the outlet portion. 
     In another embodiment according to any of the previous embodiments, the inlet portion is divided into a plurality of rectangular inlets corresponding with the second end of the plurality of flow passages. 
     In another embodiment according to any of the previous embodiments, each of the outlet portions includes a plurality of outlets having one of a pie-shaped cross-section and curvilinear shaped cross-section. 
     In another featured embodiment, a method of forming a manifold for a heat exchanger includes creating a plurality of core sections that define a passageway between an inlet and an outlet. Each of the plurality of core sections define a common inlet area and outlet area for the passageway. A mold cavity is defined to receive the core sections that defines an outer shape of the manifold. The plurality of core sections is molded within the mold cavity to encase the core sections within a casting material. The core sections are removed from the casting material. 
     In another embodiment according to any of the previous embodiments, each of the core sections defines an area ratio between the inlet and the outlet of between 1.5 and 5. 
     In another embodiment according to any of the previous embodiments, the core sections define the inlet as one of a pie-shaped and a curvilinear shape in cross-section. 
     In another embodiment according to any of the previous embodiments, each of the core sections define a smooth curved passage without interruption between the inlet and the outlet. 
     In another embodiment according to any of the previous embodiments, the plurality of core sections together define a circular inlet in cross-section. 
     In another embodiment according to any of the previous embodiments, the core defines a substantially rectangular outlet in cross-section. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an example heat exchanger embodiment. 
         FIG. 2  is a perspective view of an example plate of the example heat exchanger. 
         FIG. 3  is a perspective view of an example intake manifold embodiment. 
         FIG. 4  is a schematic cross section of a passage of the example intake manifold. 
         FIG. 5  is a schematic view of an outlet for the example intake manifold. 
         FIG. 6  is a schematic view of an inlet passage for the example intake manifold. 
         FIG. 7  is a schematic view of an example exhaust manifold. 
         FIG. 8  is a cross-sectional view of an inlet for the example heat exchanger. 
         FIG. 9  is a cross-sectional view of an example outlet for the example heat exchanger. 
         FIG. 10  is a cross-sectional view of another embodiment of an example inlet for the heat exchanger. 
         FIG. 11  is a cross-sectional view of yet another example embodiment of an intake for the example intake manifold. 
         FIG. 12  is perspective view of another example intake manifold embodiment. 
         FIG. 13  is a perspective view of an outlet for the example intake manifold of  FIG. 12 . 
         FIG. 14  is a schematic view of a method of creating and casting an example intake manifold according to the disclosed embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a disclosed heat exchanger  10  includes an intake manifold  12  and an exhaust manifold  14 . The intake manifold  12  is disposed on a first end  32  of a plurality of plates  16  with a limited number identified in  FIG. 1 . The exhaust manifold  14  is disposed on a second end  34  of the plurality of plates  16 . The intake manifold  12  defines an inlet  26  that communicates a first flow  22  to the first end  32  of the plates  16 . Each of the plates  16  includes a first flow passage  18  between the first end  32  and the second end  34 . The plates  16  also define a second flow path  20  for cooling airflow. The second flow path  20  is comprised of a plurality of fins  30  that extend upward from an outer surface of each of the plates  16 . 
     Airflow  22  through the first flow passage  18  is placed in thermal contact with the cooling airflow  24  through the second flow path  20 . The disclosed example plate  16  comprises a single unitary part that provides for thermal communication between the inlet flow  22  and the cooling airflow  24 . It should be understood that it is within the contemplation of this disclosure that other plate configurations or other heat exchanger configurations could be utilized, benefit from this disclosure, and are within the contemplation of this disclosure. 
     Referring to  FIGS. 3 and 4  with continued reference to  FIGS. 1 and 2 , the airflow  22  is of a hotter temperature and flows through the first flow passage  18  defined by the plate  16 . Cooled flow  36  exits through the exhaust manifold outlet  28 . Both the intake manifold  12  and the exhaust manifold  14  includes a plurality of separate splitter passages  38  defined within a housing  52  between an inlet that receives flow and an outlet that distributes a flow to the plurality of flow passages  18 . In the case of the exhaust manifold, the exhaust manifold receives airflow from the first flow passage  18  defined within the plates  16  and transitions that flow into the circular outlet  28 . In the case of the inlet manifold  12 , the inlet flow  22  flows through a substantially circular inlet and is divided evenly to provide a smooth uniform flow path to each of the first flow passages  18 . It should be understood that although the intake manifold  12  is described by way of example in this disclosure, that the same features are also applicable to the exhaust manifold  14 . 
     Referring to  FIGS. 3, 4, 5 and 6 , the example intake manifold  12  includes the inlet  26  and an outlet  40 . The outlet  40  distributes airflow to a plurality of first ends  32  of a corresponding plurality of the plates  16 . The splitter passages  38  define a flow path between the inlet  26  and the outlet  40 . The splitter passages  38  include smooth curved walls  50  reduce disruptions that may create turbulence and inefficient airflows. Each of the splitter passages  38  include smooth walls  50  along the curved passage without interruption between the inlet  26  and outlet  40 . It should be understood, that surface treatments and/or surface features  55  may be added to the smooth walls  50 , to assist the turning of the flow, within the passage  38 . The smooth walls  50  may include surface features  55  that assist in turning of flow within the passage  38 . The surface features  55  may include vortex generating structures such as dimples and local areas of increased roughness relative to the smooth walls  50 . The surface features  55  can be utilized in regions of where flow might separate from the walls  50  and cause aerodynamic disturbances that reduce flowrate. 
     The inlet  26  is divided into a plurality of inlet portions  42  that include a cross sectional area  46 . The outlet  40  is divided into a plurality of outlet portions  44  that include an area  48 . In one example embodiment, a ratio between the inlet area  46  and the outlet area  48  is within a range between 1.5 and 5. Each of the inlet portions  42  are of an equal area and disposed within the cross section of the inlet  26 . 
     Referring to  FIG. 7 , the disclosed exhaust manifold  14  is substantially the same as the intake manifold  12  except reversed such that airflow exiting through second ends  34  of the plurality of plates  16  enters a rectangular inlet portion  30  and exits through the circular outlet  28 . The exhaust manifold  14  includes exhaust passages  56  that like passages  38  are of an equal flow area from the inlet portion  30  to the outlet  28 . The inlet portion  30  is divided into a plurality of rectangular inlets  54 . The outlet  28  is divided into a plurality of outlet portions  58  having a pie-shaped cross-section. The outlet portions  58  may also be of other curvilinear shapes in cross-section corresponding to each of the exhaust passages  56 . 
     Referring to  FIG. 8  with continued reference to  FIGS. 3-6 , the example inlet  26  is a circular shape in cross section and is subdivided into six separate inlet portions  42 . Each of the inlet portions  42  are of a substantially equal area and communicate independently with a corresponding passage  38 . In this example, each of the inlet portions  42  are substantially pie shaped in cross section and subdivide the circular cross section  26  of the inlet into six separate inlet portions  42  that communicate with different corresponding splitter passages  38 . 
     Referring to  FIG. 9 , the example outlet  40  includes a plurality of outlet portions  44  that are substantially rectangular. The rectangular orientation and cross sectional shape matches the inlet shape for the plate  16 . It should be appreciated that other shapes of the outlet openings  44  could be utilized to correspond with shapes of the inlets to each of the plates  16 . Moreover, it should be understood that each of the outlet portions  44  correspond with in at least one or several of the flow passages  18 . 
     Referring to  FIG. 10 , another example inlet  25  is shown and includes a plurality of inlet portions  41 . In this example, the inlet  25  includes a circular cross section and includes a plurality of subdivided inlet portions  41 . Each of the inlet portions  41  is a curvilinear shape that includes an irregularly curved shape. The different curvilinear shapes are provided to fit within the circular cross section of the inlet  25 . Although example inlet portions  41  are schematically shown, other regular and irregularly shaped inlet portions  41  could be utilizes and are within the contemplation of this disclosure. In this example, the inlet portions  41  are substantially identical in area while not identical in shape and provide smoothed shape to transition into each corresponding splitter passages  38 . 
     Referring to  FIG. 11 , another example inlet  27  is and is substantially circular and divided into rectangular inlet portions  43 . Each of the rectangular inlet portions  43  correspond with one of the corresponding splitter passages  38 . 
     Referring to  FIGS. 12 and 13 , another example intake manifold  60  is shown and includes an inlet  62  that is subdivided into different inlet portions  66 . The manifold  60  includes a housing  68  that defines a plurality of separate passages  74  that extend from the inlet  62  to the outlet  64 . The passages  74  define a single unitary smoothly curved passage that reduces pressure losses. The inlet  62  includes separate inlet portions  66  and the outlet  64  includes separate outlet portions  72 . The example housing  68  including the inlet  62  and the outlet  64  is a single unitary structure without seams or joints between different portions. 
     In this example, the outlet  64  includes flanges  70 . The flanges  70  are attached to the intake manifold  60  and enable securement to the plates  16  or to supporting structures utilized to support the heat exchanger  60  in operation. The flanges  70  are shown as a separate feature from the housing  68 , but also may be an integrally formed as a portion of the housing  68 . 
     Referring to  FIG. 14 , a method of creating one of the disclosed manifolds  12 ,  14  and  60  includes a casting operation where a core assembly  76  is utilized to define each of the individual flow splitter passages  38  ( FIG. 4 ). In this example, the core assembly  76  includes a plurality of passage defining structures  78   a - e . Each of the passage defining structures  78   a - e  includes an inlet portion  80   a - e  and an outlet portion  82   a - e.    
     The core assembly  76  is inserted into a mold  84  that defines a cavity  86 . The cavity  86  defines outer surface features of a completed intake manifold. During operation, a casting material  88  is injected into the mold  84  and filled around the core assembly  76  to define the completed part. The cast part is then removed from the mold  84 . The core assembly  76  is than removed according to known procedure and processes to provide a completed intake manifold  90 . Additional finishing steps may be required to finalize the intake manifold  90  such as for example, polishing, machining, coating and other finishing processes as are known. Additionally, flange  70  may be added if not part of the cast manifold  90 . 
     The example disclosed manifolds includes features to limit pressure losses and improve thermal transfer efficiencies. Moreover, each of the manifold includes features that enable airflow velocities to be increased to improve thermal transfer efficiencies. 
     Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure.